The Daily - The Secret Power of Siblings

Episode Date: May 13, 2025

Parents try everything to influence their children. But new research suggests that brothers and sisters have their own profound impact.Susan Dominus, a staff writer for The New York Times Magazine, discusses the surprising ways that our brothers and sisters shape our lives.Guest: Susan Dominus, a staff writer at The New York Times Magazine covering a broad range of topics. Her recent article was adapted from her book, “The Family Dynamic: A Journey Into the Mystery of Sibling Success,” which was published by Crown on May 6.Background reading: Read Susan’s article about the surprising ways that siblings shape our lives.For more information on today’s episode, visit nytimes.com/thedaily. Transcripts of each episode will be made available by the next workday. Photo: Artwork by Kensuke Koike Unlock full access to New York Times podcasts and explore everything from politics to pop culture. Subscribe today at nytimes.com/podcasts or on Apple Podcasts and Spotify.

From the New York Times, I'm Michael Bobarro. This is The Daily. Much of our understanding of what makes us who we are revolves around the role of our parents. Today, my colleague, Susan Dominus, on the unseen but surprisingly powerful ways that our lives are shaped by our siblings. It's Tuesday, May 13th. Hi, Sue. Hi, Michael.

It is really nice to see you. It's so nice to see you, too. I want to jump in. And I want to have you tell the story of how it is you became so interested in the subject of siblings. So I think it started when I was a young child and my parents used to go away pretty often and travel for work. And when they did, I would stay with really close family friends.

And you may know that when you stay with a family, you really get to know them and their culture in a way that's different from your own family. You can really see all these big differences. In one family I stayed with, the kids would do these very elaborate math problems, like at the table, you know. At the dinner table? At the dinner table. One, the father would say, so Daniel, a plane is leaving Chicago, traveling this many miles an hour,

and another one is leaving New York. What time would they cross paths in wherever, you know? Oh my God, what are you thinking when that question comes across the table? I loved it, it was like a show for me. I just loved it until they asked me that question one day and I burst into tears, but. Is it safe to say that was not

the dinner table dynamic at your house? No, my father's very proud of the one rule we had at the table, which was that you had to chew with your mouth closed. And that was firmly enforced. But I became what I think of as kind of a familyologist. I got very interested in how family cultures differed and how it affected the kids in those families and their outcomes and who they were likely to become. And fast forward, I become a journalist. Perhaps not surprisingly, a lot of what I cover as a now adult familyologist is family dynamics.

I did a lot of reporting that involves twins and nature and nurture. And I really got interested in doing even more research into this topic. I ended up undertaking a book, which was going to be about the nature of families of high-achieving And I went into the book fully expecting that I was gonna hear these stories about parents who had these extraordinary ways of doing things and they inspired and motivated their kids. And instead what I found was that although parents matter certainly, the parenting effect is actually probably smaller than we think. These decisions that loving parents really agonize over, like whether to have a chore

wheel or whether to co-sleep, those things probably matter less than we think. And what I found as I reported and researched was that sibling effects are actually more profound than have been realized. And they really do matter for kids in ways I think researchers are just only now starting to appreciate. Matthew Feeney So tell us what you end up concluding about the sibling effect from your book, The Family Dynamic, which ends up very much being a study of the dynamics of siblings.

Beth Dombkowski Well, I think that there is a kind of duality to how these things work. And what I really found is that the parents sort of, the way I think of it is, parents can kind of launch this arrow of ambition and striving into the air. But the people who focus that arrow and who help it land somewhere, maybe someplace suitable, very often those are the siblings. Hmm. That's a lovely metaphor. Thank you, Michael. I wonder if you can illustrate how it actually works,

that siblings influence the direction of that arrow. Yeah, I was curious about that myself. How did that work? And one way that I got at it was by going deep with a couple of families and really spending time with them, really understanding the sibling dynamics and how they recalled their childhoods and these really influential moments. So one of the families that let me into their lives was the Groff family. This is a family of three siblings.

Lauren Groff is this much lauded influential novelist. Her sister Sarah True is an Olympic triathlete turned Ironman champion. I know. And then they have a third sibling who they also know. He's the really impressive one, Adam. And he is a serial healthcare entrepreneur who's done extremely well doing good with innovative healthcare solutions. Okay. And what do you find from the graphs? You know, the graphs embodied very neatly a concept that's known as differentiation.

This is the idea that kids are trying to find a niche as they're growing up. And so if one sibling is doing one thing, whether it's conscious or not, another sibling might go in a different direction or their parents might even push them in a different direction. So you can see where this ended up in the graphs in that they all have careers that are wildly different. Wildly different. And then what do you come to understand about how, and this seems important consciously

or unconsciously, the Groff siblings exerted a differentiating force on each other. Because that seems like it would be not something you would necessarily ever consciously intend to do. I think it happens all kinds of ways actually, but the person who's most explicit about it was Sarah, who's the youngest of the three siblings. Sarah had these two older siblings who were very, very academic. And she felt that if she couldn't keep up with them, that was on her, she said, and that her desire to keep up with them was all about her relationship to them, much less

her parents. So first of all, that was interesting to me. Right. It wasn't about pleasing her parents. It was about keeping up with her siblings and being worthy in their eyes, I think. But she also felt that she couldn't keep up with them academically. And she says that she thinks she made a conscious choice

to go into sports all in, because that was a domain where she knew she could excel. But even more than that, she knew that Lauren wasn't that interested in it. And so, you know, so she felt like- The lane was free. The lane was free. And this effort that Sarah has to, you know, find her own lane really comes to head when she's 14 years old and she tells her parents that she wants to swim the length of the nine-mile

lake that's right outside of their home. And the family all sort of, you know, they're dreading this. They don't think she's going to be able to do it. But they're like, okay, let's go. Dad rose, brothers in the sailboat with him too. And not only does she swim the length of the lake, but she actually broke the town record for men and for women. And that record still stands.

And they all agree that that was a really defining moment for Sarah. And I think she kind of came into her own and realized, ah, this is who I am and what I'm going to keep doing. And ran with it and swam with it and became this incredible triathlete. And it's really interesting because there's a lot of research actually that suggests that younger siblings are overrepresented in sports.

So there is this finding that comes up over and over again that the oldest sibling is indeed the most cognitively strong, does the best in school, gets the best grades, they have this little cognitive edge. Just explain that because everyone listening is going to want to understand why that is. Well there's different theories about it, but the one that rings the most true to me, I'll just say, is that when you're an only child, you know, your parents just shower you with a level of attention and cognitive enrichment. And they have more of that attention.

They have literally more hours in the day to spend on that first child than they do when the second and the third come along. By the way, I should emphasize that these effects are small, and they are also on average, so it does not mean that this is necessarily true for your family, dear listener, or dear youngest child, of which I am one. But it does mean that on average, this is what we see. And so when you have an oldest child,

typically being the most academically strong, then you see this differentiation, which is that younger children are sometimes more drawn to sports or they compete a little bit harder in sports in order to define their niche and find their way and have this space where they can excel. And then you actually do see in some research that younger children are overrepresented in elite sports. That's fascinating. And clearly that seems to be what happened with in elite sports. That's fascinating.

And clearly that seems to be what happened with the youngest of the Graf siblings. What about the middle Graf child? What was her experience, Lauren? So what I see in Lauren is something that's a little bit different, which is you can see in Lauren, and she's actually also quite self-aware about this, how a sense of competition with her brother was really fueling her. I don't think her brother was even aware that there was a competition, but she felt like she wanted to prove something to him.

At one point, she felt, she told me, that a huge part of what motivated her to write big, bold, feminist literature was the frustration that she felt with this all-knowing older brother. Wow. So what's important about the graphs, it would seem, is that you have this academically strong and much more than he would seem to know emotionally towering figure, and the two younger siblings respond in these complicated ways that it sounds like they're conscious of. They seem to know it's happening. And as a result, they end up in very high achieving but extremely different lines of work.

That's beautifully summed up. Thank you, Michael. Yes. Well, what about the Groff's parents? In your understanding of the family, how did they launch that, to use your phrase, arrow of ambition that the sibling, especially Adam, the older brother, ultimately influences the course of? You know, both of the Groff parents had come from very hardscrabble backgrounds and gotten college degrees and their father had become a doctor and was able to provide this really lovely life for his children. But I think it was very important to them that their children be tough, that their children

be hardworking, in part because of where they had come from. So they even have this term in the family, which is gruffiness, which is a certain kind of like hard work and like brute force, getting things done. Lauren once said to me that in her family, work was holy. And I think that is the launching of the arrow. Do these siblings get along? I mean, does differentiation mean ultimately difficulty? Oh, I sometimes think it's the differentiation that allows them to be close because the competition isn't happening.

That's really interesting. Yeah, and in fact, they are very, very close. You know, Sarah moved to New Hampshire to be closer to Adam at one point in her training. Sarah's been very open about mental health struggles that she's gone through. She's a mental health advocate. And Sarah says that Lauren was somebody who would just stay on the phone with her sometimes being there for her, even if they were very, very quiet. So the Groffs are a family with a fair amount of resources, right?

So how much do your findings, especially around differentiation, apply to families without those resources? Does that mean that there is inherently less competition, less enrichment, less differentiation? Yeah, there is some research that suggests that you see differentiation in families that have the resources to shuttle kids around to different kinds of lessons,

and there's a lot of room for individualization in those families. In less advantaged families, you don't have quite so much differentiation, but there is an equally powerful force that does shape the siblings. And I really saw this at work in a family that I got to know very well called the Chens. We'll be right back. So Sue, tell us about the Chen family and the dynamic between the siblings in that family that was at play. So the Chens were a family that had immigrated from China,

and their parents ran a Chinese restaurant. They were incredibly hardworking and worked very, very long hours. And they just weren't around as much as parents ideally hoped to be. So the siblings were extremely close, and they spent a lot of time together and they really influenced each other very strongly. And what you see in this family is a phenomenon that's called the spillover effect.

The spillover effect is just a reflection of the fact that when one sibling does well, then the younger siblings tend to do well as well. And for many years, it's been difficult to know whether that's because of genetic overlap, or is there something in the environment apart from how the siblings are influencing each other. But there's a really interesting study that was conducted just a few years ago that is sort of what we call a semi-natural experiment. This researcher at Yale found that when children are kind of on the old side for their grade, depending on where their birthday is, we know that those kids tend to do better academically than kids who are very young for their grade.

So she looked at the younger siblings of those kids who happened to be doing better in school because of this developmental advantage. And what she found was for the younger siblings of those kids, it didn't matter whether those kids, these younger siblings, were old for their grade, young for their grade, they did better than expected. And so you really see here, that is the sibling effect. It's not something that's happening at home. It's not genetic.

It's just affected by the good luck that an older sibling had in being a little bit old for the grade. And what does the spillover effect look like? How does it operate within the Chen family? So there's four Chen siblings. The oldest is Elizabeth, then comes Yi, then Gong, and then a fourth sibling who is much younger than the older ones, his name is Devin. When they arrived in the United States, Elizabeth was put into a grade that was two years below her age. Because they were so worried about her English skills that they wanted to give her a chance. Not only did they give her a chance, but I think they really gave her a boost.

Because she was going to catch up with the English pretty quickly. And then she had all these other advantages, like self-control and just being more developmentally farther along. And teachers really respond to that. And then school becomes a really comfortable place. And that was a place where she excelled. And then because she did excel in school, she was able to help her siblings excel. She would tell them which APs to take and she would help them with their homework.

And all of the siblings played instruments and she was very important in helping them practice and they all were coaching each other. That was true in a way for sports as well. So E, the oldest of the brothers, was a very accomplished wrestler. But it's not that Gong then chose some other sport, he didn't go in a different direction. He too became a wrestler. And so he benefited from his brother's expertise and they were kind of consolidating forces. There's like this symbiosis. And you know, you see these kinds of so-called spillover effects.

They influence each other in very collaborative ways. And it sounds like in this collaboration you're describing, the Chen siblings are building off one another, each one hoping that the next will do at least as well, if not better, than they did, either academically or athletically. That you're saying is the spillover effect. And it really does feel quite different than the more competitive, tinged idea of differentiation. I mean, it certainly looks like one mechanism of the sibling spillover effect.

It's the opposite of competition. It's working together and influencing each other and making each other in some ways more similar, which to them was about making each other better, basically. You really see it in their youngest sibling, Devin. They had all gone off to college themselves, or maybe were even out of college by the time he was applying to schools. And they actually felt a little bad for him that he wasn't benefiting from what they had

provided for each other when they all lived in the same home at the same time. There wasn't enough spill left to spill over him. Yeah, exactly. And so they would, you know, conference call with him and they actually formed a reading group to make sure that he was reading. They were picking books for him to make sure that he was keeping up with that. And then when it came time for him to apply to college, they actually divided up the tasks. One of them took over SAT prep and one helped him with his essays and one helped him keep

on top of applications and staying organized. And this is one mechanism of how the spillover effect works. It's Devin presumably wanting to live up to his siblings' academic success, but it's them also really sharing their resources with him. Where does Devin end up going to college, which of course makes me want to know what happens to all four of the Chen siblings in terms of their career? So all four of the Chens were in fact valedictorians. And Devin ended up going to Dartmouth. And I'll spare you the colleges, they're all terrific. But there's more to life than college. I know.

You're like, no, there's nothing more to life than college. What I like about the careers they all chose that I find very moving is that they all chose careers that sort of would have helped their own parents when they were struggling in their first years in America. So Elizabeth became a doctor who works with a sizable Chinese population. You know, I think that their parents rarely went to the doctor. I'm sure if there had been Chinese doctors in the area, they would have been more comfortable. He actually was one of the first hires at this mega restaurant software business called Toast. It's like the Amazon of restaurant software and

Gong ended up working at this very high-power AI English language instruction startup. And then Devin works in Amazon. He's a software engineer. Devin likes to say that of the four siblings, he's the one who works to live where his siblings, he thinks, all live to work. So in my time with this family, I was struck by how proud of each other they all were, how protective of each other they all were. how protective of each other they all were.

And now, of course, they're having children of their own. It's really beautiful to watch that happen. And they're all really intent on the cousins being really close. I mean, that's a remarkably beautiful story. I wonder if spillover effects on siblings are always as constructive and positive as they were with the chens. You know, that's a really important question because spillover effects, of course, can as constructive and positive as they were with the chins? You know, that's a really important question because spillover effects, of course, can,

in fact, work the other way. We know that siblings influence each other and that means that if a sibling's grades are suffering because of some outside force, that's also going to have an effect on their younger siblings. So, the concern is that if you're in a disadvantaged family, there might be some trauma, right, that affects the older sibling. Inverse childhood events, we call them. So if there is something traumatic that happens, I'm a junior in high school, maybe my grades suffer, okay?

My little sister is a freshman in high school. Her grades suffer as a result of the same trauma. But also, because the junior in high school's grades have suffered, that too has a negative effect on that younger sibling. So it's this one-two punch. And so what that tells us is that you have families that are more likely to suffer some kind of disruption like this than the grades suffer, and we know that income later in life is very closely tied to grades and test scores in high school.

So these kinds of sibling effects actually do have really profound policy implications. What do you mean by policy implications? Well, just when we think about are we going to invest in interventions, it actually turns out that if you can raise the academic performance of an older sibling, that investment in that intervention is all the more worthwhile because it's going to have ripple effects on the whole family, or more specifically, the younger sibling. And so you're not just affecting, let's say, the economic earnings

of the older sibling down the road, but the younger one too. You're getting so much more bang for your buck with an effective intervention than really has been previously realized. I'm not trying to be facetious, but this almost sounds biblical. If the eldest child is invested in properly and this spillover effect happens, that seems quite important and potentially achievable. I did say the oldest child, but I think it's possible that sibling effects can work in multiple directions.

And does that mean that younger siblings can spill over to older siblings? Yes, that is what that means. Hmm. So now that we've talked through these two distinct but seemingly related forces of the spillover effect and differentiation between siblings, I wonder what you have found in your reporting on how controllable any of this is. Parents like to think, and you hinted at this earlier, that they exert some level of influence over this kind of thing. Can they?

Do they? Or is it ultimately out of their control? You know, I think that parents think they have more control than they actually do over so much. And trying to really change one child is kind of like checkers. And then the idea that you're gonna try to actually manipulate some complicated interaction over many years among multiple siblings, like to me that's just like playing chess with a blindfold on.

So, you know, there's some common sense things that I think parents aspire to, which is not to compare too much. And if they have the resources to let children, you know, pick their own passions and foster them. But I also think that some of the things that drive sibling relationships, such as competition and rivalry, you can manage it, but you can't necessarily control it. I don't think we can end this conversation without asking you about your own siblings and your relationship to them, with them. Is it a story of spillover? Is it a story of differentiation? Is it a story of spillover?

Is it a story of differentiation? Is it a story of something else entirely? I think in terms of personality, there's some differentiation there, but it's also, I think, this idea of the arrow being launched and the sibling helping it land somewhere. I really see that in my own family because my parents definitely valued hard work.

That was a huge value in our household. But my brother was the person who came to me when I was 14 and said, why don't you join the high school newspaper? He was at college at the time. And I said, we don't have one anymore, it disbanded. And my brother then launched into a big lecture about the decline of democracy without a free press, and it was pathetic. And he kind of rallied me to try to restart the high school newspaper.

And I was a pretty passive kid. I spent most of my time reading in a room. But my brother knew me well enough to know. He knew before I knew that I would love doing journalism. And I think if my parents had suggested it, I would have rolled my eyes and thought it was something they thought I should put on my application. But also, God bless my parents had suggested it, I would have rolled my eyes and thought it was something they thought I should put on my application. But also, God bless my parents, they were really laid back people. They weren't the kind of people who were paying that much attention, you know?

And so it was my brother who was paying attention and who knew the school environment. He knew me. He knew what high schools were supposed to have. And somehow his belief that I could do it, I actually did go out and do it. I'm not saying it was a great high school newspaper. It was not, but it was, I loved doing it. And from the second the first article started trickling in, I just was like, oh, this is what I want to do.

And so it was a really fateful conversation that we had that day, and I definitely am grateful to my brother for it. I mean, let's just be explicit about how fateful. Oh, yeah. we had that day and I definitely am grateful to my brother for it. I mean, let's just be explicit about how fateful. Oh yeah. I mean, I found my vocation. Because? Because my brother told me to do it.

Told you to do it? He didn't just tell me to do it. He kind of bullied me into doing it. Like I didn't want him to come home from the next vacation and be like, why didn't you start a high school newspaper, you know, and then start lecturing me all over again? I didn't want to disappoint my brother. And of course, there's something kind of poetic about this. If your oldest sibling hadn't pushed you to create that newspaper and become a journalist, you would never go on to write a book about siblings.

That's true. And I think it is because I've been very lucky in that way that I've also been really drawn to the subject And on that note because I'm not talking about my family. Oh damn sue. Yes. Thank you. I had a question for you One last question tomorrow. Okay on the daily. Thank you. So I appreciate it. Oh, just my pleasure. Thank you for having me. We'll be right back. Here's what else you need to know today. On Monday, the stock market soared and thousands of American businesses celebrated as the United States and China agreed to drastically reduce their tariffs against one another for the next three months. Starting tomorrow, the U.S. will reduce its tariffs on Chinese imports from 145% to 30%. China in turn will lower its tariffs on American goods from 125% to just 10%.

Negotiators from both countries will now seek to reach a permanent trade deal, but few believe that either country will ever return to the sky-high tariffs of the past month. As a result, the S&P 500 rose 3.3%, the Dow Jones Industrial Average surged nearly 2.8 percent, and the Nasdaq climbed nearly 4.4 percent, officially entering a bull market. Today's episode was produced by Asli Chaturvedi and Ricky Novetsky with help from Claire Tennisgeto. It was edited by Michael Benoit and Mark George, contains original music by Marian Lozano and Dan Powell, and was engineered by Chris Wood. Music is by Jim Brunberg and Ben Lansford of Wonderly. That's it for the Daily.

I'm Michael Bobaro. See you tomorrow.