Modern Wisdom - #667 - Nancy Segal - What Twins Separated At Birth Teach Us About Nature vs Nurture

Episode Date: August 14, 2023

Nancy Segal is a professor at California State University, an author and one of the most prominent twin-study researchers on the planet. What makes you the person you are? Is it your genetics or your environment? When twins are either accidentally or purposefully separated at birth, it presents a fascinating view into this debate, shedding light on the influence of both traits and environments on the outcomes we get in life. Expect to learn the craziest similarities between twins who have been raised apart, how it's possible to have a pair of twins born at the same time to two different fathers, what happens when twins meet for the first time, what you can learn from triplets that you can’t learn from twins, just how big of an impact genes and environment are on the traits we see in people, how important of a role chance plays in our lives and much more... Sponsors: Get the Whoop 4.0 for free and get your first month for free at http://join.whoop.com/modernwisdom (discount automatically applied) Get a Free Sample Pack of all LMNT Flavours with your first box at https://www.drinklmnt.com/modernwisdom (automatically applied at checkout) Get 5 Free Travel Packs, Free Liquid Vitamin D and more from AG1 at https://drinkag1.com/modernwisdom (discount automatically applied)  Extra Stuff: Get my free Reading List of 100 books to read before you die → https://chriswillx.com/books/ To support me on Patreon (thank you): https://www.patreon.com/modernwisdom - Get in touch. Instagram: https://www.instagram.com/chriswillx Twitter: https://www.twitter.com/chriswillx YouTube: https://www.youtube.com/modernwisdompodcast Email: https://chriswillx.com/contact/ Learn more about your ad choices. Visit megaphone.fm/adchoices

Hello everybody, welcome back to the show. My guest today is Nancy Seagalm. She's a professor at California State University, an author and one of the most prominent twin study researchers on the planet. What makes you the person you are? Is it your genetics or your environment? When twins are either accidentally or purposefully separated at birth, it presents a fascinating view into this debate, shedding light on the influence of both traits and environments on the outcomes we get in life. Expect to learn the craziest similarities between twins who have been raised apart, how it's possible to have a pair of twins born at the same time to two different fathers. What happens when twins meet for the first time, what you can learn from triplets that

you can't learn from twins, just how big of an impact genes and environment are on the traits we see in people, how important a role of chance plays in our life, and much more. This was very, very interesting. I love Nancy's work. She is at the intersection of behavioral genetics and evolutionary psychology. She's great, and I really, really hope that you leave feeling all sort of warm and fuzzy and insightful about human nature. She's got a great energy and it's evident that she just adores the work that she does. She's in love with the research and bringing twins together and finding out more about human nature. It's really, really great. Also, one week today, Alex Homozi is back on Modern Wisdom. This time, for episode number three,

I recorded with him this weekend in Las Vegas, in person with a full cinema set up. I know God, it's good. So, so good, and I cannot wait to get this one out. He's one of my favorite guests to bring on the show, and I really, really hope that you will enjoy it. Obviously, you need to make sure you've hit the subscribe button, or you're going to miss that episode and many more when they go up. So go and

press it. Thank you. In other news, this episode is brought to you by Woop, the 24-7 Health and Fitness Coach that helps the best obsess over the details that matter most. Woop tracks your sleep, strain, recovery, stress and more to provide personalized insights that help you reach your goals. So, whether you're obsessed with squeezing a little more effort out in the gym or getting in those extra hours of sleep, Woop helps you build better habits and make healthier choices.

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How do you describe what you work on when somebody asks? Well, I tell them that I'm a development of psychologists, but my interests also cover behavior genetics and evolutionary psychology. And I'm passionate about twins because twin studies are a simple and very elegant way of combining all three developmental psychology, behavior genetics, evolutionary psychology, different levels of analysis and application. But also, I'm between myself. And so I really think that when you're personally invested in something, you have greater interest

and passion for the topic. And so my whole career, I like into a candy store. I've just had a wonderful ride. And the ride is continuing. That's how I feel when I get to speak to anyone from the EP world or the behavioral genetics world or the sex research world. It's the absolute most fun. William Costello, the guy that's doing all of this stuff on in cells at the moment, famously keeps on reminding me that research is me search. It's a little bit different for him doing it on in cells and you doing it on twins given the erotone. I don't know what it says about William given that that's what he's studying.

What is the evolutionary psychology angle of twin research? I can see how behavioral genetics comes in. You know, we're splitting apart genetically and environmentally what the contributing factors are. But I'm less sure about the others. Right. So, one of the, you know, very provocative theories that was launched was Kinship Genetic Theory by William Hamilton, who asserted that we feel great cooperation, altruism, investment

in people with whom we share higher degrees of genetic relatedness. We don't consciously do the calculations in our head, but we behave as though we do. And so I've always known for years that identical twins are more cooperative, closer socially than fraternal twins are on average. And so I thought that this was another level of analysis that I could bring to twin studies because many people say, well, they're closer because they look alike, and people encourage it,

but I know that's the case because behavior is not built on a pair, as behavior is built on the brain. And so I always thought that there was some deeper level to this. And so I've been able to use twins. I've been able to use unrelated lookalikes. I've been able to use virtual twins. Many, many types of relationships are very in genetics and in environmental connectedness.

And the findings are beautiful because they really converge on the same thing. You know, I remember when I was doing my doctoral dissertation, my first major study, and I used seven to eleven year old children, twins, and what I did was I put them into a puzzle completion situation, I kind of semi naturalistic study where they all completed the same puzzle under the exact same circumstances with the exact same instructions. And without a word for me, and I kept the mother's out of there, the identical twins just did this orchestrated dance, beautifully coordinated. There was little rough play. Everybody was very cooperative and they were very successful at puzzle completion. But the fraternal twins, on the other hand, tended to grab different pieces of the puzzle to their side of the table and worked on it independently. And the whole thing looked like a mess. And there were lots of elbow jabs and snatching of pieces. And so that really told me that twins can tell us so much just by being themselves.

What is your explanation for why identical twins and fraternal twins had that difference? For the people that don't understand, am I right in saying that fraternal twins are essentially just simultaneously born brothers and sisters? That's correct. Identical twins result when a single fertilized egg divides between the first and 14th age of conception, whereas fraternal twins result when a mother releases two eggs at the same time, separately fertilized by two sperm. And so the kids share 50% of their genes unaviged by descent, which is at the same time, separately fertilized by two sperm. And so the kids share 50% of their genes

on average by descent, which is exactly the same as ordinary siblings. So I think that what is going on here, Chris, is that identical twins who have the same genes are responding to the world the same way they have similar temperaments. They process information the same way. And so all those ingredients allow them

to work more cooperatively in a joint situation, whereas fraternal twins bring very different interests and understanding and abilities to a particular task. I can tell you that I have a fraternal twin sister, and in a puzzle-pleased task of kids, we'd be in each other's throats. We had very different understandings and ways of doing things, and we still do. We're close sisters, I think a lot of siblings get closer as they age. But nevertheless, as children, we would have been definitely on the competitive side.

I wonder whether teams, it would very much depend on what the activity is that you're doing. But I can imagine some activities in which you want someone that's very similar to you. But in other activities, you might actually want someone who has a different skill set. You want to be the analytical one, you want them to be the creative one, you want to be the slightly more risk averse one, you want them to be the slightly more adventurous one. So I imagine that depending on what the task is at hand, you could have scenarios in which being identical twins would be an advantage or sometimes a disadvantage. Yes, I think that's right. For example, if you're a very skilled, say, at coming up with great ideas, but you don't know how to put them into play, you might want somebody who's more analytical, more

statistical minded to really compliment you. And so to that degree, somebody a little different would be helpful. But identical twins would probably just pick a topic or pick an area where they both excelled and they do very well at it One area I'm really fascinated in twins and sports and it is amazing to see these matched Levels of elite athletes, you know, it's extraordinary one person wins in a Olympic event But even more extraordinary when the other one comes in second. How is this possible? Part of it is because of the way their bodies are built, their similar motivations, their similar interests. And the fact that in many cases, a single victory for one is a victory for both. And it's hard to get your head around that kind of selflessness. But

I've heard it repeated so many times. What about that? What about the degree of emotional connection between identical twins? I mean, there's tales as old as time about they've got secret languages, and they can mind-read and do stuff like that. But have you found, comparing it with normal siblings and fraternal twins, is there an extra degree of connectivity,

of emotional investment of kinship, as would have been predicted by that theory? I think there's no question that there is an emotional connection that goes far beyond any kind of relationship. In fact, I would assert that the identical twin bond is closer than any other relationship. Even more than mothers with children. And I would, I say that because I have a study on the loss of a twin, on bereavement,

and I wanted to understand two things. Do identical twins grieve more than paternal twins, mirroring what you see in their relationships and is there something unique about twin loss? And of course, this was all framed by evolutionary theory, particularly kinship genetics. And I did find that identical twins grieved more for their co-twin than they did for any loss of any other relative, whether it was a father, a non-twins sibling, a grandparent, an andro uncle. Of course, when you get to those, you know, second degree relatives, the genetic related is dips down. I'm guessing that's the same for a son or a daughter as well then.

Yes, yes, but well, let me backtrack on that. I have very few sons and daughters, very few twins lost children, for which I'm very grateful. But that would be theoretically, it would be a fascinating comparison because with identical twins, you share all your genes with children, only 50 percent. Whereas for trunnel twins, you share all your genes with children only 50%. Whereas for tunnel twins, you share have an average with your twin and you share 50% for sure with your child. So I would expect much greater variability among the fraternals.

Very interesting, but I really hope I never get to do that comparison because I don't want anyone to lose a child. I, one of the other very interesting things that I learned about when looking through your research is that there are times when a mother will release two eggs and will have multiple sexual partners within that pregnancy window, within that fertility window and end up with, I don't even, what are the, like half, half twins, like what, what are they called? Well, the medical term for that is super fecundated twins, which means that because she had two eggs released and she had two different partners, each partner got to one egg in that four-day fertilization window and the children are

really genetic half siblings, but I regard them as illegitimate pair of twins because this can come out naturally and it can also come about through artificial reproductive assistance. You know, as you know, and I've told you, I have a book that's coming out August 8th called Gay Father's Twin Sons, the citizenship case, the capture of the world. And this is a case where two gay fathers who were very much in love with each other and married decided to raise a family. And so they contacted a donor and a surrogate, and they each provided sperm to fertilize these eggs. And it turned out that the top two embryos were each, uh,

insept, each created by one father. And those are the ones they implanted. So they replay an actually occurring situation. Tell us that. Tell us that story. Well, what happened was there was a young man named Andrew from the United States who decided to get a master's degree at Tel Aviv University. And then he met another young man, Elad, and they fell in love and married in Canada in 2010. Tel Aviv, Tel Aviv isn't fantastic for trying to get your gay wedding across the line.

Not really, no. In fact, Israel now will recognize gay marriage, but they won't allow it in their country. If you marry elsewhere, it's recognized. At any rate, they moved to Canada because gay marriage was allowed there their country. If you marry elsewhere, it's recognized. At any rate, they moved to Canada because marriage, gay marriages allowed there in 2010 and Andrew also had dual citizenship. In 2016, they decided to have a family and that's when they gave birth, these beautiful boys, Aiden and Ethan. And the problem became when the boys were four months old and they decided to move to Los Angeles. And when they tried to get the boys the passports at the consulate in Toronto, they were just

hit with a number of very rooted intimate questions, such as where do these children come from? Who's the father of this one? Who's the father of that one? Intimate details that they had no plans to reveal not even to their parents. The only ones who knew were DNA lab and and the circuit, beyond that nobody knew the relationship of the kids. So now, their genetic linings are all hanging out on the clothesline, everybody knows.

And so the upshot was that they issued a passport to the little boy who had, who's created with a sperm from the American father and a tourist visa to the other one. And so this threatened the Taylor family apart. Tourist visas are good for about six months. They are renewable, but it was a terrible situation. So when they did come to the US, it was about 2017-2018, and that was when when former president Trump issued these bans on Muslim immigration. So all the immigration attorneys were at the airports taking care of these cases, but they did find a wonderful

group in New York called immigration equality. Lawyers that are very concerned with gay couples, HIV infected individuals, other minorities, and they work pro bono on behalf of these couples. And Andrew and Elijah's case came about at the perfect moment because they already had three other couples transnational who had children outside the US. But Chris twins capture attention and this case really got into the media because the idea of separating two little boys who were born four months apart is unconscionable.

And that was the real threat to the family. So the case was the family's name, Davosh Banks versus the US State Department and Rex Tillerson who was then Secretary of State, later Mike Pompeo. It was a very high profile case that almost reached the Supreme Court. It took four years to resolve. There were moments when the government appealed. You have an appeal window of 60 days and they would appeal on the 59th day after the Circuit Court ruled

in favor of the family. Eventually, the case settled no more appeals. And now they're living out here in California. I can't tell you what a lovely family they are. And all you see when you look at them are two really devoted parents and two very happy children. That's it.

You don't see anything else. Wow. What is to it? How much of this do you think is concealed homophobia from organizations that maybe, and then I guess actually a combination of concealed homophobia and concealed Islamophobia intersectionally combining to create this. I think that is certainly one of the factors, and I think whether you're a homophobic or not, if you just simply disagree with the idea of it, then I think that that can play a role

at the point. with the idea of it, then I think that that can play a role in it. Wait, sorry, maybe homophobia might be the wrong term there, that just there's less preference given. It's not like you need to discriminate against, but it's a slippery slope from, well, is the treatment the same? I'm going to guess that it would be treating somebody different on the basis of their sexual orientation, probably that's a rough definition of homophobia.

So it probably meets the criteria, not quite the same as going out if you're way to call somebody a slur, but if you're not treating them the same way that you would do as a heterosexual couple or a couple that are both from a European country or whatever, yeah, maybe it doesn't meet the criteria. Yeah, so at any rate, I think that's really plays into it.

And then there's another element that I noticed that one of the lawyers brought to my attention. And that is that the government just seems in some ways to make things difficult. I don't know why, but they just seem to make things difficult for these families who just simply want to lead their lives. And so many politicians say families first,

and yet, what about this family and The wonderful thing about this case was it did settle in favor of the family and it has been helpful to Future families the far and affairs manual, which is what is relied upon in the consul it was modified because of this and It's still the case that officers have some measure of discretion in interpreting some of these guidelines and rules. But nevertheless, it's gone far and these two fathers could have taken an easy way out. They could have gotten a green card for the child. They wouldn't have had any publicity. But they were both very eager to make a statement and to leave some kind of lasting change in society.

They both had difficult times growing up as gay men, as gay teenagers, they both, and so they know what it was like to suffer and to stay strong and to make a difference. And so that was an attitude they carried with them into this issue as well. And I think they're terrific. I mean, they're just terrific.

Right now they're over in Europe having a vacation. They're doing it all families do. And in fact, one of them said to me, we're boring. Said, all we do is we take our kids to Disneyland. We watch Netflix. We go to the market. And we're just boring people. It's just that we happen to be 2K guys.

And they're right. They are boring. But I love them. I am very, very glad that you've managed to find such an interesting story and was it three identical strangers, that managed to do something very similar with regards to just captivating people's attention. You said it earlier on, there's something about twins, especially identical twins and triplets that are just so captivating.

One of the things that you brought up earlier on that's still playing on my mind was you mentioned the kinship genetics prediction, the closer you are genetically related to somebody, the more you should care, the more that you would be invested. How is it that twins know that they're twins in this case. Well, that's a very good question. And I think they know when they can see the other one looking like them, or even if they in the fraternal twins,

you're there someone they've grown up with, they've been in the house. Now, in evolutionary psychology, there are two cues that have been talked about in terms of sibling relatedness or knowledge of the the sibling is one of these the Western arch effect because this is my favorite I Wasn't gonna go there, but we can go there later because I think that's really fascinating I have talked about that and I'm gonna tell you some stuff that's gonna start all you but all right

Let me just go with this for a moment so so the two cues that have been talked about in terms of sibling knowledge, knowledge of a sibling is maternal association. So if you see another baby with your mom, you figure that's a relationship to you and the amount of co-residents. So if you live with the child, another kid, that means that that's probably yours. That's interesting, but it's not enough because most identical and maternal twins live at, with same mom, same dad, same house. And yet we still have these differences in social relatedness between the identical and

the fraternals. Nobody teaches them that. So I think that it's recognizing similarities. And it goes beyond just the physical feature. Because as I told you you earlier I do studies of Unrelated local likes who look as alike as identical twins and they are nowhere as alike in personality and very few of them develop close Relationships that are lasting just to interject there what that would prove is that the reason that Identical twins are the same is not because people treat them the same. Yes, but Right because they evoke similar treatment from others

So see I'm sort of turning the process around. I do think people treat identical twins more alike But it's because they evoke similar reactions from people and we call that evocative Gene-environment correlation in behavior genetics. This is called So at any rate, I think that with identical twins, whether raised apart or raised together, they perceive certain similarities of themselves that draw them together. Beyond their appearance, it's their mannerisms, their interests, their temperaments, all those kinds of things. I've seen close relationships evolve in no time. I worked for nine years

on the Minnesota study of twins raised apart, and I could see these things evolving very quickly between twins who recently met, and I actually had demonstrated this quantitatively. I had identified paternal twins rear to part. Tell me how they felt when they first met, how they feel now in terms of closeness and their initial feelings of familiarity and current familiarity. The identical twins were significantly higher on most of those than the fraternal twins. But an even more revealing question that I asked, which I'm so grateful I put in, was I asked all the twins, how do you feel in terms of

closest of familiarity to the adopted sibling you were raised within your home? Very few said very close, very, very few. And that's rather counterintuitive. You think, well, I should feel closer to the people I was raised with. It's not so. It's just not so. So what this counters a little bit is the theory that it's just to do with seeing your mother raise somebody it's just to do with co-residency during that early years window because if it was the case then the way that you look in terms of similarity or personality type that level of resonance between you and someone that you meet in later life would have relatively

limited impact. Also one thing I've been thinking about, you know, in a modern world where we've got mirrors and we've got cameras and we've got a phone that's got a high definition video recorder in it, we see ourselves, but for almost all of human history, we didn't see ourselves, right? How would we, other people would be able to say you look like them.

What about, what about lakes and ponds? You could look in there and kind of, it wouldn't be as sharp, but you still have the sense of who you look like. And I know that some of the, some of the older cultures had very shiny glass or metal where they would look, so it's not like today, but you certainly could get a sense of what you look like. Now, I wanted to talk about the thing you mentioned before. So the Western Mark effect. Right. So that is very, very fascinating. And I've not documented this, but I have noticed that when identical twins are raised together and both are gay, they're almost never each other's partners. In fact, they have relationships outside the home, virtually all the time.

And that could be a result of, you know, familiarity breeds contempt if you want to call it that. But there have been, there was a pair of identical twin men raised apart that we studied the University of Minnesota. And when they met, they became each other's lovers. Now, it's only one case. I went back and looked at the biographical material in previous redepart twin cases, and there were a couple of cases that kind of hinted at that sort of a relationship.

So I wonder if it works the same way. No one has really ever looked at that because the percentage of identical twins and fraternals raised apart as relatively small, but you could probably do it with siblings. Now, there is a concept in the adoption world called genetic sexual attraction, and it's been talked about mostly with mothers and sons who reunite and fathers and daughters, and it's not even that they necessarily have intercourse with each other, but this mother described this feeling she just wanted this close physical contact. And sometimes this does go into sexual relationships.

It can, but it doesn't necessarily have to. Now where am I going with this? Because I've documented five or six cases of male female twins who've been separated at birth and to meet and marry. And they describe a fierce attraction, probably based on the similarities they perceive in one another, and the way that their relatedness is discovered is because they usually have a child of the genetic defect, because remember that every parent

carries a lethal recessive. And if you marry a sibling, or you have, two siblings carry the same lethal recessive, the chance of a child would be 25% if that couple got together. So at any rate, it's devastating, of course, but some couples split up, some don't. It's very, very interesting. And I also, along those lines, noticed that when we had separated male,

female twins in our 11, Minnesota, there was absolutely flirtation going on. There's no question about it. Wow. Okay. So here's a question for you. What does the state think about accidental incest? You know, I don't know the answer to that question, but because some of these couples are allowed

to marry, and I don't think that they've been from this country, most of them have been from Europe. And as far as I know, no one has forced them to separate. If they separate, it's their own choice. Isn't that interesting? That we almost carve out an exception for the fact that we know there is a very small cohort but not insignificant of twins raised apart for one reason or another fraternal twins because that's such a shit i was thinking one of the things i wish that you'd be able to work out would have been sexual a version or an increase in the western market effect. or an increase in the Westham architect, if there was such a thing as identical twins that were different sexes, it would be... Oh, if they were raised together, I bet that's right.

But these are twins raised apart, and the attraction comes in. Now, I think that that is something we have to worry about, and some countries have started worrying about this, because now, you know, with all the sperm donors creating so many hundreds of children in some cases, you have to worry that if the mother is living the same local area, these kids may be about the same age, and so half siblings might get together, and they might be attracted to another just a way that separated twins and siblings are. What have been some of the craziest similarities between twins who have been raised apart that you found? Yeah well I have to think about these twins Oscar and Jack who had

the most amazing story. Oscar they were born and turned to dead to a Romanian Jewish father and a woman from Nazi Germany, Catholic, they were born in 1933. So Nazism was just sort of on the horizon. The marriage failed. And so one boy was raised in Trinidad with the Jewish father, the other raised in Nazi Germany when they hit their youth. And so when they met, of course they had very different political and historical understandings. But they both read books back to Front. They both

used to wash their hands before and after using the toilet. They both thought of a hysterical sneeze loudly in elevators, and they both thought very upset if they were in a restaurant, and there was a vase of flowers in the middle blocking your view of the other person. They used to collect rubber bands around their wrists. I mean, they had a lot of these very odd idiosyncratic matches. And a lot of people think, well, it's co-incidence. I don't think so. I think these are hard scientific data. I honestly do. The trouble is you can't start setting rubber band wearing around the cross cases. But what you can study, Chris, is you can study the frequency of these odd similarities

in identical versus paternal. And I can tell you that we found them much more in identicals than in fraternals. In fact, in the Minnesota study, we had one pair of paternal twin men, were both at 18 tattoos. We counted them. Now, I'm sorry at this point, we didn't look at the types for the flowers, or the women, what were they? We didn't do that, but we found 18. And I actually have a paper that came out earlier in 2022 in the premier issue of the Japanese Journal of Twin Studies. And my students died that this project,

where we looked at the similarities in twins from the Minnesota study and from previous and past studies. And of course, when a similarity is something like using crest tooth paste, I mean nobody cares about that, half the world uses crest tooth paste. But we had a pair of twins that used a rare Swedish brand called Baddie Makeum. And so you have to wonder, you know, what attracts them to this weird stuff. So maybe they like to do things differently, or maybe they like the taste. Who knows?

Or maybe they have this vanity with Sweden. But the beauty of these kinds of things is that they give you new hypotheses about why you do what you do. For example, we had a pair of fraternal identical twin males who both held the beer can of only Budweiser with their pinky finger and knees. Now why would you do that? It could be because your hand is made a certain way or you worry about spilling the beer and you want to be very secure about it.

You just like the way it feels, something like where you think it looks cool. At any rate, it gives us new ways of thinking about these kinds of things. And let's face it, all of us have odd behaviors that we do that we hope nobody finds out about. But I'm willing to bet you that they're not just there because they're there. They're there because of you, because of the way your body and your mind are constructed, and you prefer doing things that way, then alternative ways. Yeah, I fear that there's a twin, an unseen twin out there of me doing all of the embarrassing shit that I do privately and letting other people know about it. I'm thinking about what you spoke about.

These things seem relatively arbitrary, what type of card you drive, what sort of toothpaste do you use, how many tattoos have you got? But they're very discreet individual examples that explain an entire suite of traits that somebody has, right? So as you said with the can, is it because it feels good? Is it because that's the particular size of your hand and the can slips out? You've got particularly small hands, particularly big hands or whatever, right? What it shows is a physical manifestation that's very obvious about, that represents something that's going on internally and sort of biologically too. What it suggests is that if we were able to visualize thoughts on some super intelligent

fancy FMRI machine in a hundred years time, the texture of their mind is probably likely to be similar. The sorts of ruminative thoughts that they would have, the things that they wish that they'd said or didn't say, the number of words that they say per minute, the number of ums, ears and likes that they speak, you know, all of this stuff is determined by a combination of your physical attributes, the morphology of your mouth, etc. But then also what's the predisposition that you've got mentally? Well, sure.

I think that all comes into play. I absolutely do. And I'm not so impressed, as I said, with the common similarities. It's the rare ones that I find intriguing. And those are the ones we focus on. So, for example, I did something with names in that Japanese journal twins how often they name their children the same name and we looked at the frequency of how often names were that name in those years. So you know, you can start to quantify

some of this stuff and get some very interesting findings. Wasn't the, was it the gym twins? There was some incredible case. Yeah, the gym twins did too. Unfortunately, both of them passed away. They're the ones who met at age 39 and actually launched the Minnesota study. They lived only 40 miles apart, no higher. And they used to bite through nails. They described a headaches syndrome

as someone pounding on your head. They used to scatter love letters around the house to their wives. They had woodworking benches. They drove the same kind of light blue Chevrolet. They vacationed on the same three blocks strip of beach in Florida, amazing they'd ever met. They had they had numerous similarities and they named their sons James Allen and James Allen. One Allen had a nail, two else one had one. I know you can laugh about that but why would

you name what goes into name picking obviously the other partner has a Asane is too, but maybe because they were first born sons They wanted to name their son after their own name very traditional and or maybe the name Alan Reminded them of somebody like the way it sounded. I don't know. I'm just throwing out ideas But it just gives you a new and fresh way of thinking about these things, not just chalking it up to random chance. Didn't they have something to do with the marriages as well? Yeah, so this is interesting.

One of the gym twins married Betty and divorced her married Linda, divorced her married Sandy. Now, the other one also married Sandy, divorced her married Linda. If I were Linda, I'd be a little nervous. and also married Sandy, divorce chair married Linda. If I were Linda, I'd be a little nervous. Because Betty's coming around. You want to expand you came into the atmosphere, I'd probably go running.

So interesting. And again, you think about all of the different inputs that we have on our behavior, all of the myriad interactions we've had with the world, the books that we read, especially if we've been raised apart, different books that we have on our behavior, all of the myriad interactions we've had with the world, the books that we read, especially if we've been raised apart, different books that we read, different, whatever, whatever, and yeah. They read similar books when they read the part. Well, there we go, but it's just this permanent gravitational pull towards your predisposition. I think so. We all have choices in life life and we live in most of us do live

in communities and cities where there's lots to choose from. And yet there are certain things we choose and certain things we don't. And I think that's why identical twins are alike because they pick and choose the same things that are compatible with who they are. And the very, again, another kind of counter-intuitive betrothining is that genetics, genetic effects seem to go up as we age, and people think, how can that be? It should be environment-making more of an impact, but it isn't, because once you get away from home, and you're not under the thumb of mom and dad anymore, you're free to pick and choose, and that's why the early studies of religious interest showed no genetic effects,

because they were studying children raised at home by their parents. So both twins had to do exactly what mom and dad said. But once they left the house, you began to see the genetic effects kick in because then they would gravitate towards similar types of activities and really express themselves and sports participation works the same way. Very little genetic effect when you're young at home starts to kick in when you become an adolescent. Does IQ is point eight by the end of life? Pretty much. The heritability is about 80%, 75 to 80%. Yes, that's another one that shows increasing genetic effects as you age because you're constantly refining your interests, your activities, all that sort of stuff that feeds into mental skill.

But you would presume a lot of people, the behavioral genetics denies out there would say that all of the different inputs you have, your nutrition, your hydration, the amount of vitamin D that you've got, where it is that you live on the planet, the kinds of things that you get exposed to, you know, all of these are going to, in their eyes, it would mediate your ability to deploy your IQ and yet, behavioral genetics seems to rule all. Well, genetics, no, genetics does not say it's completely genetic. I mean, there's nothing is a correlation of one. I find the most fascinating thing is that there's so much out there that can make us

different. And yet identical twins are still remarkably alike, whether they raised their part or raised together. But again, you know, you certainly with nutrition, I mean, one twin is exposed to a condition other one isn't, you know, there are cases where one had COVID, one didn't, that sort of thing. So certainly with infections, I mean, there are many things that can make you different, but it's not like it makes you different in every way, you might be different in one area, but very still very similar in others. I've also had the opportunity to work with twins, identical female twins, where one felt like a male and actually went through surgical reassignment to become a male. And yet the twins' restore marker will be alike in every other way,

except for this one fundamental difference. And what was so wonderful to witness was just how welcoming the non-changed twin was. And if she wanted her now brother to be happy and content, and the brother wasn't for many, many years. What about psychopathologies, schizophrenia, depression, anxiety, alcoholism, other sort of maladies like that? What is the insight that you've learned with regards to fraternal and identical twins?

Well, identical twins are more likely to match on all of those than fraternal twins. There's a genetic component and everything you rattled off. Schizophrenia is about 40 to 50 percent. It's nowhere near one. The one that the only psychopath ologist is really the strongest genetic effect I've seen is autism at about 70 percent. And that can also vary depending on whether you strict or lose your criteria. But bipolar disorder has a genetic effect. Dementia, breast cancer interestingly does not. It's about 20% similarity in females. Well, so you could have identical twins, one of who just get breast cancer and one of whom doesn't. Yeah, that's very, very interesting.

You know, see, those cases are extremely informative for the general public. A lot of people think the twin research is only for twins, but it's a model of looking at human behavior in general. And so you could look at a pair of identical twins. And so one has cancer, one doesn't. Why? Why? What about the environment that triggered it in one twin and not in the other?

And that's really important information by way of prevention. Diabetes is another one. You know, one twin has it is about 50% match. Multiple sclerosis is another one. Twins, it's funny because identical twins is so alike, but they're less alike than people think they are. Both are really true. I hate to say it, but it is. What have you learned about twins that are raised apart and BMI or weight? Yeah, so it differs from males to females. The similarity is higher for males. With females, there are various hormonal effects, exercise, diet, so females are a little bit more flexible in that way. But body mass index, BMI, does have a genetic effect as does height weight.

body mass index BMI does have a genetic effect as does height weight separately. Yeah, it's that was one of the most interesting things that I learned because a lot of the time and this gets on to what is it that you call it the gene environment covariance? A correlation? A correlation, that's it. That in a household, let's say that you have identical twins, it is very difficult once both of those twins are in that household to pass apart what is the contributing factor of the nurture element here and what is the contributing factor of the nature element here. You see fat parents with fat children and you think that that's because of their lifestyle, you know, look at this, but there's a huge genetic component to people's weight.

And you don't know how I had Robert Ploeman on the show. He told me this really, really great insight. I can't forget. He said he has a predisposition to overeat. He said he's a secret fatty. And what he means is that he walked past a bakery and the smell of bread to him is just so alluring. And he told me this thing and he said,

there are many ways to get fat. What he means by that is there are unbelievable suite of different routes towards being anything that you want, right? Being conscientious, being industrious, being fat, whatever it might be. It may be that your grueling release is higher than typical. That's the hunger hormone release in your stomach. It might be that you comfort eat because of the way that your mental dissonance, it may be that you really don't like exercise. You are low on energy. It may be that, you know, pick your myriad of reasons of how people can gain weight. So when you look at people who do gain weight, you presume that it's all from the same root, but it's not necessarily, it can come from places.

It can come from multiple sources, of course. And see, that's the danger in studying intact nuclear families, because you can't separate out the genes and environment, they're all confounded. You know, for example, parents pass on both genes and environments to their children. So, if the parents are very bright readers and the child is too, how do you know it's not the genes, how do you know it's not the reading experiences as some combination of both? That's why you have to apply these developmental designs that separate them out. So one, the very simple one is the classic twin monocygotic, identical twins versus fraternal twins. Another adoption studies, twins raised apart, you want to disentangle the genes of the environment. That's what you want to do.

Many developed mental psychologists study parents and children and they come to the conclusion that it's environmental influence, but it's not. It's all confounded. It would be as if I was sick and I took drug A and drug B and got better. Well, how would I know if it's drug made me better? I wouldn't know.

See, it's the same exact thing. You can't figure out what's causing what. The other interesting thing I always think about this is that because you have a predisposition genetically to be interested in certain things and to behave in particular ways, and your children will do too, therefore your behavior, which is predisposed by your genetics and your children's predisposition and the environment that your behavior puts them into all start to exaggerate each other. Now, this isn't to say that children are one-to-one with their parents' traits, that's not the way that it works, but the point being that when you see particular outlines,

I have a friend here in Austin, Aubrey Marcus, the guy that founded on it. And I'm pretty sure his father was, his parental, his actual biological father was some inventor guy. His stepfather was a very, very impressive businessman, and that was the person that raised him. His mother was a world champion tennis player, and he went on to sell this business for half

a billion dollars at age 35. You go, well, you've got the genetic components, you've got the foundations here and then look at the environment that you grew up. It's not a particular surprise that in adulthood, you had a very high bar for yourself, super conscientious, very industrious, worked hard and succeeded. Yeah, I know. That's not surprising at all. On the other hand, you know, parents can have two children who are extremely different. And one child might thrive in the environment

that's provided by the parents, and one child will absolutely refuse to go into the family business. So siblings and the family differ by a great deal. And the home environment is not the same for all children. Parents can provide all the sports that could make you want, but one child may thrive on it, one child won't even go near it. One child may stay on the computer the whole night and the other child won't go near it. If everybody fashions their own environment, within the setting that they find themselves in.

It's not. There's so many majors we could all be, right? Universities offer tons of different majors but we pick one or two that are interesting to us and we don't even consider the other ones. Why is that? It's not strictly. And I have no interest in being a lawyer. My sister, my twin sister is a lawyer but I have no interest in it. Have you looked at anything to do with birth order? Effect. I know that it's not strictly a twin relationship.

The trouble with birth order is, well, you can have birth order effects with twins, but if the parents treat the first born one as the older, that could have some sort of an effect. With twins, however, you know, if the twins are born in a cesarean section and what happens to be a minute old and the other I think to make a big deal over that means nothing now the only way that birth order can make an effect with twins Is if it's a vaginal delivery and the first born has a much better situation than the other because the uterus Changes with the birth of a baby making it much more difficult for the second child so that child may have changes with the birth of a baby, making it much more difficult for the second child.

So that child may have more adverse influences as a young baby and will need a little more catch-up period. So that's where birthwater plays a real role. But in C-sections, it doesn't. I think that a lot of these birthwater studies with twins don't take that into consideration and just lump everybody together together and it's ridiculous. Is there anything that you can learn from triplets that you can't learn from twins? It depends on the configuration of triplets.

If you had triplets composed of an identical pair and a fraternal, I love that kind of triplets and I've opened a couple of these because what you find is that the identical tend to be really close and really similar and the fraternal feels like the odd man out. And I've seen that in many, many cases. If they're all identicles, you know, I mean, it's basically three pairs of twins. So you can match everybody by which way. And if they're fraternal, you can certainly win a lot too. But I think that the most interesting one are same sex, we are two are identical and one isn't. And what I if I had to devise an experiment, just pick one up, I would never

do this, but I would like triplets like that. And I would give away one of the identicles. And I would be more like the identical that they weren't raised with or the fraternal. And I bet, you know, my money would be on the identical. Wow, that would be so interesting. Yeah, I'm not saying anybody should ever do it. I don't think twins should be raised apart, so I want to be very clear on that. Yeah, what's the ethics or how do you feel when you're observing a lot of these situations and you have what you've managed to identify

in your opinion as the closest human to human bond on the planet, literally the closest that you can feel to somebody else. And then they get raised apart. So what are your feelings on the ethics and the discomfort around that? And then what happens when twins meet for the first time? Well, the ethics are very interesting.

And in my 2021 book, The Liberally Divided, I go into that a great deal. And this goes beyond three identical strangers. It's a really in-depth analysis of the Louise-wise adoption agency that had a misguided view that identical twins should be raised apart because they grew up with their own identities. And then the Seaglass study that followed these children

up until the age of 12, that telling them or their parents that they had a twin. So separating twins for that reason, this misguided developmental theory, I think is unconscionable. Now, I will say that sometimes twins get separated for more legitimate reasons. So maybe a mother dies in childbirth,

or the family can't afford to keep them. But the parents separate them or the family separate them with the children's best interest in heart. I'm still not condoning that, but I do think it's understandable. And twins have also gotten separated through odd circumstances. We had a pair where the twin was visiting her grandmother in mainland China and the other twin was in Taiwan and because of political developments, they were raised apart. She couldn't go back and be reunited with her family, the one from mainland China. So these things can happen. Now my perspective is that, oh, and also I have a study on the twin children who were separated indirectly

through the one child policy in China. And these are twins who are separated partly sometimes because the mother gives away one and keeps the other, and then maybe gives the other one away later, or they're brought together to an orphanage and then somehow they're separated because people don't realize their twins or whatever. But my view and the view of my colleagues who are in this line of research We believe in bringing twins together and we don't believe in keeping them apart for research reasons In Minnesota, we would sometimes encounter twins who'd never met and we wouldn't keep them apart You know for research reasons. Yeah, maybe you want to separate them. We would never do that

In fact, we made an incentive of the study to bring them together so they could spend time together. And we would test them separately. You know, we told them not to discuss the test while it was still ongoing, all that sort of thing. And they took it very seriously. I've no doubt about that. But I'm completely against twins being raised apart. Sometimes private adoptions happen where a mother decides to keep one and give away another one. I mean, I think it's unfortunate that these things happen. But I would be of the opinion to never separate twins. I just don't think it's unfortunate that these things happen, but I would be of the opinion

to never separate twins. I just don't think it's right. I think it's a violation of a birthright. What is it like? Have you been there when twins have met for the first time? What's that like? I have. It's amazing.

It's the most wonderful experience you could ever imagine. And twins do different things things some jump up and down Some hug and kiss some just kind of look at each other sometimes they they touch their face and touch their twins face at the same time But it's amazing. It's sort of this moment of out of control glee and You can't help but feel the same joy that they're feeling. Eiffel, most of these people who are adoptees who never look like anybody who raised them. And suddenly for the first time, they're meeting this celebrated relative and identical or a fraternal twin. And it's a big deal.

It's a very big deal. I mean, I sometimes say to people, what if you learned that you had a long lost cousin, would you go look for them? Well, modest interest. Have I an uncle or an aunt? Maybe. Parent. Absolutely. Identical twin. You bet. It's irresistible. It's just irresistible. Why do you think it is that so many people have a problem with behavioral genetic explanations for the traits that we have? I think when people hear the word genetics, they feel that whatever that trait is,

is non-changeable and is set in stone, and that could not be further from the truth. Behavior is, after all, the expression of a gene in an environment. And if you modify the environment, you can affect the genetic expression. I will say that some traits are harder to change than others, but you can engineer an environment,

you can work harder but you can engineer an environment, you can work harder, you can get into training, you're not stuck with the things. Now, for example, we know the divorce has a genetic component because identical twins and we're likely to divorce both of them than fraternal twins. But your genes don't tell you to divorce, you make the decision. Maybe you have a difficult personality or you're very fussy about your partner or whatever the reason is, but you make the choice. Your jeans don't tell you what to do. You are the one in command.

Yeah, I see a lot of this on the internet, especially coming out of the dating, sphere, the black pill and the in cellcell movement that William in particular studies, you know, behavioral genetics to me was just what it was the second most fascinating thing that I learned about after evolutionary psychology. And I adored looking at this, not necessarily a conflict, but this tension between my predisposition and the outcomes that I got, what I had the role in terms of raw materials and, what I had in terms of raw materials and then what I had in terms of environment that impacted that. But a lot of people do get fatalistic

after learning about behavioral genetics. They believe that they have a very heavily capped ceiling that it's this sort of deterministic life that they're living now. I am doomed to be X or Y or Z. Yeah, no, that's really not the case. I mean, maybe you're doomed to have brown eyes or hazel eyes, but even then you can get colored lenses if you really want to make the change. But let's face it, I mean, somebody who may be six feet tall will probably never be chosen

for gymnastics. There are certain limitations, but I think that's good to know that. It makes us predispose toward more realistic decisions and lifestyle changes. So I think it's good if you know that, say, your parents are alcoholics, suppose you learn that. Well, you can use that information. You're not necessarily going to be alcoholic, but you might watch how much you drink, drink a little more carefully, things of that sort.

So I think it's wonderful information that we can all use. How do you conceptualize or explain to people this relationship of genes and environments when it comes to outcomes in life and how that should inform our behavior and the way that we see ourselves and our efforts? Exactly what I just said, that you can alter environments and affect genetic expression. I give examples of things like that. You know, I'll tell you, the people who I find the most intelligent about this are the parents of fraternal twins and siblings. They know more about human behavior and have a more reasonable view of it than my colleagues,

many of my colleagues. They just know that what works for one child doesn't necessarily work for another and many of them went into parenting thinking that everything was environmental. And they come out, but with completely different ideas, as do reunited twins, I interviewed every reunited twin in the Louise-wise adoption study. And a lot of them said that they really felt that behavior was environmental, but they'd never met a twin before. And suddenly, they're learning about themselves, that their behaviors are not just coming out

of nowhere, but they're coming out of somewhere. And it's a great education. It's just a great education for them. How much? Let me just mention, I also did a book recently this year on the twin children who survived the Holocaust. It's an annotated photograph collection. I think I told you about that.

And these are the twins who were in the mangle experiments in Ashwood, Spurkinow in 1945. And I went with them to the 40th anniversary reunion in 1985. And why did these twins survive when some other ones didn't? It's an interesting question. Luck had a role here too, but a sort of resilience and strength. And the twin bond too, the strength of that bond gave them each kind of a will to live, which was so important, which non-twin survivors didn't have the benefit of.

Hmm. Thinking about the parenting side of this, how much can rearing change a child? Well, I can't give you a number, but what I can say is that I think parents have a very important role and I think it's different than how people conceptualize it. Parents do not mold you into what you are. I regard parental responsibility as being very sensitive to the child's individual tastes, temperaments, likes, dislikes, abilities and interests. And I think if parents can be attuned to that

and really help the child to become more of who they are and to maybe overcome some of their drawbacks like shyness or timidity in some situations. Then I think that's a great responsibility. It really pained me when parents, when mothers who were still pregnant and rolling their children in these prenatal programs of education.

I mean, it's ridiculous. I think that good parenting is really sensitivity to the child and being very supportive and nurturing. So I think parenting makes a huge difference. I think children who grow up with insensitive parents or multiple caretakers who don't take the time to really see what their interests are, are the ones who are not going to benefit. Yeah, Jeffrey Miller once tweeted that every parenting book combined is less useful than one book on behavioral genetics for parents to read. I think it's very well put. I would agree with that.

Yeah, it's just, I try and look back, you know, I'm an only child, so I try and reflect on my own life, and I don't have another, an A, B split test of me to be able to look at, to be able to compare. There's some parts of my personality that I do see from my parents, but there is so much that's different, like so much, it's incredible. And I would say that my parents predisposition in terms of the way that they're set up and the environment that I grew up in was quite aligned.

I don't think that they changed themselves massively when I was born. All of, obviously, all children will change parents. It's a massive life switch. But yeah, I love the idea of helping a child to find out what is their passion, what is their calling, what it is that aligns most with them because for an individual parent to try and reverse engineer or to prescribe in advance,

I always, you know, the classic story of the father that didn't get picked for the football team. So, you know, my son, he's going to be the football player and he's two years old throwing a football, like Christmas and stuff. That prescriptive role, in some regards, is good because it creates guidelines that children can follow. But if you're continually having to reinforce your child to do that because all he wants to do is play music or draw or whatever, you're fighting a losing battle. Yet, yes, you are. And that's why I think that parents of fraternal twins and year and age siblings are the ones

that really understand human development. These fraternal twins can be extremely different. My sister and I went in very, very different directions. I took ballet. She took drama lessons. We went to different schools, different summer camps that were more suited to what we wanted. And my parents were very good about that. They didn't force us to be together.

It was easy because children in their own way will tell you what's best for them. If parents will only take the time to look. Hmm. That's a lovely insight. And I think when I first spoke to Ployman about this as well, he, he, the sense that I got, I'm not a parent yet,

but the sense that I got from a parents perspective is that it alleviates a lot of the pressure. I think that parents feel. Yes, I think that parents who are less well informed about what parenting is all about feel they have to do everything.

And if they just relaxed a little bit and paid attention and took the cues from the child, I think they'd be a lot better off and they'd be much happier and more effective parents. Yeah. I know, no forms about saying that. Yeah, I think so too. And there is, you know, in a meritocracy, if you are your successes, then it also means that you are your losses too, right? And we know that people have very different, as soon as you take the behavioral genetics pill, like forget equality of opportunity, forget that,

right? Way before equality of opportunity is equality of genetics, which is just not, it's not going to happen between everybody. So as soon as you take that behavioral genetics red pill, what you realize is that largely your child's outcomes in life are going to be determined by the part that you chose to have them with, right? And you can do things to improve that. You can make the quality of their life better.

But if you're, you know, tiger mopping your way to hope that you can create a 140 IQ child, I, it's, you're going to be disappointed. Keep in mind, too, though, that suppose you've got two parents who are very interested in dancing or sports or something like that, they get a bit of a child with absolutely no interest in that whatsoever, because the genes reshuffle in every generation. And, and then also what's popular in one generation may not be popular in another. And even if a child has a certain ability to align with that of the parents, there may be something else that's that's grabbed me everybody's attention in the generation to do it to the child that's born.

So these things, you know, have all kinds of factors affecting them. Parents and children I, are actually less alike than people think they are. We do see similarities, definitely, but children are very different. And I think it's largely because they get different suites of genetics and they are in environments in generations where things can be vastly different. Yeah, I think I'm really seeing this in my generation. So I would be pretty much slapping in the middle of the millennials. And I would probably guess that aside from sometimes when there's been global pandemics like

the Spanish flu or world wars or gangus cans come through or something, that this block has had from parent to child the largest inflection point in terms of the difference of environment that we found ourselves in. You have parents that grew up without the internet. So for me, I was not internet native, but I think the internet would have come online maybe when I was 11 or 12, something like that. So I've got a little bit of time before that and a good bit of time before smartphones, but relatively digitally native, but the difference, the difference in my dad's upbringing in the 60s and 70s and mine in

the 90s and the 2000s is a different universe. So yeah, you know, even if you have, even if you were one to one with your parents in terms of your genetics, look at how different, all of the different inputs are that you've got, the opportunities that you have, the influences, the chance to actually display this behavior in a completely different way. Yeah, the differences are extraordinary. They are. There's no question about it. And yeah, we can't account for everything, but I think we can account for a lot.

You know what it makes me think about? I have a friend, Johnny, that comes on the show quite regularly. And someone asked a question four or five years ago on the show and they said, if you could go to dinner with four people, alive or dead, who would it be? And you know, you've got the typical idea of thinking about, it would be Muhammad Ali and would it be Socrates

and would it be Plato and would it be Jesus. And Johnny's answer was that he would love to sit down with all four of his great-grandfathers, because he thinks that he would learn an awful lot more about himself from sitting down with them than he would. Yes, and this is a benefit that the Internet has given us that we can track our families in many ways that other people never could.

And there's a real interest in that now too. I regret the fact that I didn't ask my grandfather more questions about his coming over from Russia. I think I would have learned a lot. But still, there's ways of tracking things and many twins have found each other because of the internet. When I was in Minnesota, we thought that we had exhausted every pair of rear-to-part twins in English-speaking

countries. And that was so wrong. It was so wrong. So many have met on the internet by posting a video, not even knowing they were a twin. Just I said it a pair of twins born in South Korea. And one was raised in New Jersey, and one was raised in a very posh French suburb. And the one from New Jersey moved to LA, was an aspiring actress, put a video of herself online, a friend of the other twin sought and said, you look remarkably similar. And that's what led to their reunion.

It's absolutely amazing. And you know, this gets back, again, to something we talked about a little earlier. I think the idea of finding someone that looks so much like you or is so much like you. Now there are websites for finding people who look like you, these unrelated look-alikes, and not only that, there are websites for finding a piece of art, sculpture, a painting, a drawing in a museum that looks like you.

And we don't go looking for something that looks different than us. Children's imaginations of friends are always for someone similar. And I think that's all such fascinating and very revealing information about human nature. People who see identical twins are fascinated. And I think the reason they're fascinated is because we all learn to expect individual differences in behavior and appearance. And so when we encounter identical twins, it looks so different. It challenges our beliefs in the way that the world works.

And it fascinates most of us, but it can still turn off some people who are nevertheless intrigued. Some people may say it's too much closeness, too much similarity, takes away from individuality. But everybody is intrigued nevertheless. And I think that's why, whenever anything happens to identical twins, it's in the news. I mean, it's in the news all the time. These? And I, you know, I get these cases that I get contacts from journals all the time that one commentaries on unusual cases.

And in fact, right now I'm working with the Guinness World Records book on compiling the updated set of twin records, which is a lot of fun. Did you say that you've studied or managed to try and track down every pair of identical twins in the English-speaking world? No, no. I said that when the Minnesota study concluded, we thought that we had had every pair in the English-speaking world.

It was a very naive conclusion, because there were so many out there, there were so many people who don't know their twins, and there were people who didn't have the means to find out if they suspected, but now they do. And there are people out there for Trinnell twins who will never find out, because they don't have the advantage of mistaken identity. Many twins meet, I wouldn't say many, but a number meet because of mistaken identity. Somebody confuses one for the other. And then that's how it all comes about. But fraternal twins don't have that advantage. And so, when I think back to the Louise-wise adoption study of twins separated birth, virtually all those identicals met through mistaken identity and the fraternals did not and I wonder where other fraternal twins

Out there were separated and will never ever know And I think that's a shame. It's got me thinking This is only very tangentially related to your work. I've been thinking for a little while about related to your work. I've been thinking for a little while about interracial couples and then the children that they have. Oh, I'm doing a study on that, but keep going. Okay, all right, so my bro science, not your real science, we can get on to that in a second. My bro science was I would be very interested in looking at parental opinions and perspectives on race relations. Let's say that you have a white mother, black father, and then mixed race child,

but the gene is relatively dominant, so it's going to be a dark child. So I would love to speak to the mother and work out what it's like to be completely uninvested in racial discrimination, personally uninvested, you can altruistically be as invested as you want. And then immediately upon having a child for this to change, and he would be the second one,

and this would be the craziest one, if you were able to have the, I can't remember what the name was when you have two eggs that get released and two sperm that go at the same time. But if you had that, but those were interracial, that there was, you had a white and a black. Okay, let me tell you something. I'm very interested in the so-called Viracial Twins 2. And these are fraternal twins that are born to mixed-race couples.

And I got interested in this because in one of my classes I had a pair of fraternal twins. One looked very Hispanic and one looked very Caucasian and they did have a Caucasian mother and Hispanic father. And they told me that their life experiences were extremely different despite being raised at home in the same communities. Everybody thought that the one who looked Hispanic was a dumb one when in fact it was just the other way around. And so there have been many more mixed raised couples lately and they have fraternal twins.

And so now I've interviewed probably 10, 15 couples because I want to understand the different life experiences of the kids and what the parenting challenges are. And I also am trying to get at the topic of do you feel a greater kinship of the kid that looks more like you racially than the other one? And that's a very hard concept to get across. I mean, you can't say who do you love more? You can't say that, but I wonder if I can somehow tease that out in maybe a less direct way because it's an interesting question.

And I also wonder if there is less paternity uncertainty in mixed mixed couples. There might well be, I don't think anyone's ever looked at that, but that's something I can think about at the same time. But it's really, biracial comes from the press and the media. It's not a term that makes sense to me because they're not biracial, they may look biracial, but they're equally biracial because they have the same parents. Okay, I understand that. What are the common criticisms that you encounter around twin studies, whether it be methodology, conclusions, pushback, that sort of stuff?

What's most common? It's probably mostly methodological. People think that when twins are together, they learn from each other, that sort of thing, or they're not tested separately. And I think some people think that the conclusions are overdrawn. But I would argue that the critics have not done the studies themselves, and they probably never encountered a pair of twins. I mean, so many people who have these hard opinions don't have the experience to really make the appropriate judgments. And you know, and also so many studies that have used different populations, different

subject, polls, different protocols, conversion, the same conclusions. In my book 2012 where I give a whole overview of Born Together Rear to Part, which is the Minnesota study, I reprint from one of our papers a graph showing the acute correlation from four or five different Rear to Part Twin studies, one in England, one in Denmark, one in the US, one in Sweden, different populations, different time points, different protocols. And they all converge on the same basic conclusion about 0.75 is the genetic effect. And it's rare to get that kind of repetition, replication, I should say, in the behavioral science. It's a very robust finding. Yeah, I was going to say, you know, for the people who like to throw the term replication crisis around and point the finger at fields of psychology and social sciences, which is very justified.

The two places that you really shouldn't be pointing the finger at behavioral genetics and evolutionary psychology, because both those. Lots of repetition there and lots of converging evidence. And I really love that because it's different methodologies and different people. But even if you go outside of the Hebron genetics and evolutionary psychology, you can see studies done in social psychological theories and they come out with the same thing, but there were interpretations of different.

There's a one of those studies in the 50s where they simply asked twins, you know, who would you miss most in the event of death, twin, mother, and while there was some little variation against my studies, it was basically very remarkable that genetic relatedness was more aligned with higher levels of grief.

So if you look in that literature, you still see this stuff. It's just that the interpretation and the theoretical layering is so different. What was their justification for it? What was their interpretation of that effect? You know, it really wasn't interpretation. It was a sociological study. It was mainly to see what if what is out there. They really didn't have an interpretation. It was basically what if. Go at you. But the what if aligns with the the abrogenetic and evolutionary psychological interpretations. Damn right. It does, which is why we're interested in it. Now, you mentioned that, you said about the study that you've done. Is your study one of the biggest or the biggest in terms of twins, or is that Robert Plumman's

study that he did in the UK? You think the Minnesota study? Yes. Oh, no. The Minnesota study is not my study. I worked on it for many years and I still work on it. That was Dr. Thomas Bouchard, the director who actually launched that. Now, keep in mind that was a rear to part study. So we ended up with 137 pairs for more identicals and fraternals.

Plum and study is twins raised together and he has thousands of pairs. So definitely going to have more. Yeah, I think it was every set of twins born in the UK between 1991 and 1994 or something, right? Something like that. It's something like that. And those kinds of data sets are remarkable. But I will tell you, honestly, Chris, that there's nothing I like more, that being in a lab of twins and seeing it up close and personal, because you really see your data in action.

And I think there's no substitute for that. And I remember one of the international twin congresses which are held every two years, I organized a film session where I showed films about different aspects of twin ship. And I remember some people coming up to me and saying they love seeing this because all they do is work with data. And you know, I work with data too, a lot of it. But I also work with the real human stuff. And when I bring twins into the lab, I just love it because again, just by acting naturally as twins give you all kinds of new interesting ideas and you take some human development.

Did you watch the Netflix documentary, tell me who I am? No, I didn't. Nancy, you must watch this. I'm running it down now. You must watch it. For the people that haven't seen it, it is, I wonder if it's... What is the name of it? Is this the one? I think it's some of the identical twin men and they had a secret. Is this the one? Yeah, they have a secret.

One of the guys loses his memory and then he has to be... I did see it. I did see it. Yes, and it's remarkable. I didn't know that. I couldn't remember that was the title, but yes, I did see it. I did see it. Yes, and it's remarkable. I didn't know that I couldn't remember that was the title, but yes, I can see that. It's remarkable. Yeah, for the people, I won't spoil it, but for the people who are interested in this, three identical strangers, absolutely fantastic film, bond together with a part, your book, awesome, awesome breakdown of this. And then that, that tell me who I am is harrowing. And you see,

you see what got me thinking about it was you saying when you're in the lab and you see the twins and so on and so forth. And yeah, on this tell me who I am, you see these guys reveal this life long secret to each other. Yeah. On set. And it's the first time it ever happened. It is. to each other. Yeah. On set. And it's the first time it ever happened. It is. Yeah. It was remarkable. It was crazy. It was a film that we talked about for a long time. And I will say there's another film about the Louise Wise Adoption Agency that I think is also excellent called the Twining Reaction, which didn't get as much attention as the others. It was made by Laurie Shenseki, an independent filmmaker. It came out just about a year before three identical strangers.

Also, very excellent. And many of the twins are in both films. You know, when you think about naturalistic observations, one of the best films I've ever seen was done on 16 millimeter, back in the 60s, by my thesis advisor at the University of Chicago. And what he did was he filmed identical and fraternal twins once a month over the first year of life.

And he looked at their reactions to strangers. So in every month, he'd show them with their mother, with their happy and playing, with a stranger, and maybe with this new toy, and how they reacted to that. And I'm telling you, it was remarkable, because the identities were so coordinated that young age, fraternals were so different. It was amazing.

It's a beautiful film and I wish more people would do film. This is something that came up with the conference I was at just last week, the Internet Society for Human Ethology and Detroit. And it's a shame that more people don't use film. It really is, you can look at it so many times and get new ideas and it's, it tells things in a way that text just can't. Nancy Siegel, ladies and gentlemen, Nancy, I absolutely love your energy. I love your passion for your work.

I'm very, very glad that you came up to me at HPS and, and, and, I costed me to one side and I've been looking forward to speaking to you for ages and, and, and super, super excited to see what you do next. Where should people go if they're interested in the work that you're doing, what books should they start with and what ones have you got coming out and all the rest of it? Yeah. So I have a website with one of my twin books and one of my related material and that is Dr. DR Nancy Segel.

So DRNACYSEGALTwins.org. So drna and sy sc g a l twins dot org and I update it very very often and I have eight books out now my ninth one is coming out in August that's gave father's twin sons the citizenship case that captured the world. Then I might want to look at my photo book on the Holocaust twins. There's a lot of interesting stories about twinship in there. And deliberately divided, certainly, deliberately divided twins and triplets adopted apart inside the inside story, something like that. But if you're really, really new to twin studies, you might want to check my 1999 book called Entwined Lies, where I cover many, many different topics on twins.

I cover the biology, the psychology, reproductive interests, legal cases. I work as an expert witness on legal cases, local death, injury custody, all kinds of things like that, very, very fascinating. And right now I'm gonna be on leave for a year and I'm developing a new book proposal, which is going to be kind of a comprehensive book, kind of the, the Tom on Twin Studies. So I'm excited about that.

Yeah, very cool. Nancy, I appreciate the heck out of you. Thank you very much for joining me today. Thank you, Chris. I'm glad I coasted you. Offends, yeah, yeah, offends