Twin Similarities and Differences

How twins’ similarities and differences impact them across their lives

Twin expert Dr Nancy L. Segal shares her insights and findings from a myriad of twin studies and researches she has done over her career.

As a fraternal twin herself, the author of 9 books and over 250 scientific articles, and the director of the Twin Studies Centre, she has invaluable experience when it comes to twin similarities and differences, and how to nurture their identities.

Transcript:

Smadar Zmirin: Okay, so welcome to Dr. Nancy Segal today. She's joining us from California, and Dr. Nancy Segal is a fraternal twin, but she's also a professor of Psychology and the Director of the Twins Studies Center and authored 9 books and approximately 250 scientific articles, which is impressive, to say the least. So welcome, Nancy, and thank you for being here today.

Nancy Segal: It's my pleasure to be here.

Smadar Zmirin: I think my 1st question I mean, there is so much I would like to know about your work over the last few decades. But I guess let's start in the beginning. What drew you to study human behaviour and twin behaviour?

Nancy Segal: Well, I've always been interested in human behaviour.

And being a twin was always a fascinating experience for me, because I looked so different than my sister when we were children. I still do, and yet we grew up alike, and we grew up with the same family and school and everything, and I just wondered, as a child, how can we have so much in common in our environment to be so different? And so when I got to school and began to take more science classes. I learned about genetics.

And then I'm a great believer in genetics. It's not everything, but it's important. And I realized that she and I were just very different children. We were just like ordinary siblings, but we happened to be the same age, and we just went our separate ways. We've gotten much closer as adults, but as children I think we had pretty much our own friends, our own interests, things like that.

So I've been very interested in studying twin relationships. That's my specialty within this field.

Smadar Zmirin: Yeah, I bet I I've read in one of your books you were joking. That being a fraternal twin, you're kind of second-class twin.

Nancy Segal: Yeah.

Smadar Zmirin: You do have the privilege of kind of having invisible twinship sometimes, because people won't necessarily assume you're a twin. You can decide whether you disclose that or not. So how would you feel like your upbringing is a twin or your twin identity influenced your childhood, and later on your adult career?

Nancy Segal: Well, in terms of my childhood I always felt a little special, because I felt like there was something I had in my friends didn't have. I had a sister with the same age as me, and that was very special and very different.

But beyond that, people didn't really treat us like twins, because we were in separate classes at school, and even different schools after a while. So we had very separate lives, but it certainly influenced my choice of a career, because within psychology there was nothing I loved. I liked a lot of it, but I didn't love anything until I began to study twins, and I came upon it kind of by chance when I was looking at a paper on school separation, and that was a very important topic for me, because it was.

It affected a lot of things in my life. And so when I did the research for that, I just loved it. And so I knew after that that was going to be my specialty, and as I've gone on in my career, I am just so amazed by how many new topics come up.

Twin research is a really simple and elegant way of looking at all kinds of genetic and environmental influences on human behaviour and development. And I just amazed at how many new topics and exciting twin pairs I find all the time. And I'm writing 2 new books. Now. One is is going to be about what twin relationships tell us about other social relationships, and the other is going to be kind of a career narrative all about me and my career, and infusing that with the research that I do.

Smadar Zmirin: Wow, okay, looking forward to that. And how do you feel that your twinship, your relationship with your twin sister, has influenced your relationships actually in your life?

Nancy Segal: That's a very, very good question, and I think that as a fraternal twin, I was always a little bit envious of identicals, because they seemed to be so close and so intimate.

And we just weren't. We're very close now, but it's not that same connection that identical twins have. And I think that sometimes I was always searching for that with someone, so I think that's probably part of it.

But beyond that I really can't say. But that's a good question, and I think that's something I need to address in my books. I haven't done that yet, but I think I will, so thank you for asking.

Smadar Zmirin: Oh, you're welcome, I mean, do you feel that being a twin has impacted your choices in life, your behaviour, your sense of self?

Nancy Segal: Well, I think certainly my sense of self, because, as I said, I feel different and special. I still do. I did as a child. But I still do this way because it's kind of a privileged relationship. Not everybody has it. And it's kind of fun being a twin. We have fun with it. Sometimes we have the same voices. That's 1 thing. We have been able to trick people on the telephone. That is fun. Once we bought each other the same birthday card just once in our whole life.

So that was fun. But other than that, I think in terms of the impact, it's been more on my career than on my sense of self. But when people ask me about my background, I always say I'm a twin, and I kind of say it with a sense of pride.

Smadar Zmirin: I think you should. I mean, it's personal. But I mean, I can imagine that. Yeah, especially being a twin specialist and researcher. It's a nice-to-have, you know, next to the title definitely.

Nancy Segal: Yeah, I mean being a twin and studying twins has taught me that if you are personally invested in your topic, I think that that is what really draws you to it and keeps you there. I think there's a lot of people who are dissatisfied with their lives in terms of their work.

Very few people are as passionate as I am about what I do, and I think the people who are the other twin researchers who study twins. You know, they're the ones who are twins. I remember once I was at a conference, and it was amazing. Someone took a picture of us the front row. And when we saw it later, we realized that all the 8 people in that front row were twins, as, in addition to being researchers. It was kind of amazing. It was completely unplanned.

Smadar Zmirin: Oh, yeah, but I imagine it will have quite yeah. And a wow effect.

I mean, I will address all the stuff that from your book and your Ted talk as well in a moment. But I actually wanted to ask you, because you've been doing this for so long, and it might be hard to pinpoint. But the 1st things that come to mind what are some of the I don't know, the most interesting things that came from your studies so far that really made you think like, wow like didn't see that one coming, or oh, that explains so much.

Nancy Segal: I think there's so much I could say. But the 2 that come to mind initially well, the one actually is that so much of my work has been useful to attorneys, and I never thought about that. I've done a study on the loss of a twin and a lot on twin relationships and attorneys have used me as an expert witness in cases involving wrongful death, injury, custody, even cheating. I was in a very high profile case about 2 years ago, and now I've learned about a new area of the law which involves mixed credit reports where they accidentally put one twin's credit ratings into the other one, and maybe make all kinds of mistakes, and that gives twins so much headache because they can be accused of fraud or denied financial loans and things of that sort, and I'm even talking to a twin next week who had this on top of everything else. Her twin sister had passed away. So she's dealing with the grief of that plus a mixed credit report. So I'll be able to talk about these things with attorneys if more cases arise and the twin loss, I mean wrongful death cheating. You talk about twins who are falsely accused of cheating when identical twins. Just think the same way and turn in naturally similar projects and exams and papers. So I mean, there's so much that educators and professors and attorneys need to learn about twins, and they're you know they're the rates are have climbed in the last. Well, since 1980. They're starting to level off now because IVF is having fewer embryos implanted at this point, if they can successfully have one as opposed to in the past, where they put in 4 or 5 eggs. But yeah, so I think that that's really incumbent upon everyone to learn more about twins. At this point.

Smadar Zmirin: Yeah, definitely, I came across that in your book in entwined lives about the notion that parents even need to just understand that if they have identical twins. They may have, as you say, like, in tests, they might think exactly the same, and it will look identical. But it's not because they're cheating. It's because they're thinking very, very similarly.

Nancy Segal: Yeah.

Smadar Zmirin: And you. I remember in that book you also talked about how a lot of studies show that identical twins reared apart leading very similar and sometimes even identical lives. And I don't know. For me. It made me kind of think, maybe you know, identical twin parents can put less emphasis and pressure on, you know, fostering the sameness, it seems like the blueprint is already there, regardless of what we will do if they are gravitated towards something they will pursue.

Nancy Segal: Yeah, I think that's a good point. I think that parents should just let kids be themselves.

And if the kids, if the twins want to pick similar occupations or friendships or activities. Just let them. That's their natural inclination. And as long as twins do well in school have friends are happy, then why impose a separation on them? I just think that's unfair. So I believe in letting twins be twins and celebrating the relationship as long as they can function on their own, you know. That's important, too.

Smadar Zmirin: Okay.

Nancy Segal: They're not always going to have their twin next to them. But yeah, I think, in fact, in many ways, I tell parents you don't bring up your twins. Your twins bring you up because parents really respond to what twins are doing as opposed to shaping them. I think parents have a little less control than they would like to think. They have.

Smadar Zmirin: That's interesting. And yeah, I found it a lot with some twin parents who come to their parenthood with certain expectations or visions of what they would like it to be. And then the twins teach them that. Yeah, you may have your plan, but we have our plan. And this is actually how this is going to go.

Exactly. I think in your, it was in your Ted talk that you talked about how parents of 2 children realize that what works for one doesn't really work for another.

Nancy Segal: Yeah.

Smadar Zmirin: And have you felt any pressure at all growing up with a fraternal sister who doesn't look very much like you did? Because I saw in your books that you were not really forced to be very the same, or very similar. But did you feel anything from your parents? Any inclination to be one way or another, to be opposite?

Nancy Segal: No, no, my parents were very, very fair, and they just responded to us like 2 different children. They gave us whatever we wanted. If you know we did, we had different interests. She took drama classes. I took ballet. There's never any pressure for us to be different or similar. They just treated us in terms of what we kind of shown, showed them what we wanted, and that was really very nice. I think they were very good parents. In that respect they were very fair, you know they were fair, but I think that fair parental treatment does not necessarily mean exactly the same treatment. Fair treatment means giving each child the kind of support that they require.

Smadar Zmirin: Yeah, same instead of, you know, fair and equal. Give each what they.

Nancy Segal: Yeah, yeah. I mean, if I mean, I took ballet. Now, if my sister was forced to take ballet she wouldn't have been happy, and I wouldn't have wanted to take drama lessons. So we each did what we wanted, and that was fine.

Smadar Zmirin: And that's very progressive of them, considering. You know, it was in a different time where maybe there was less information about how important this can be for twins growing up either fraternal or identical.

Nancy Segal: There certainly was less information in those days. In fact, I think that mothers of twins’ clubs in the United States didn't start until the sixties. So yeah, there was less information out there, and people pretty much just kind of did it on their own. But my parents were very good in that respect. They were great believers in individual differences, and they respected them.

Smadar Zmirin: That's wonderful to hear. And I mean, I can see that you're working with twins at different ages. And that means that a lot of times you do come in contact with their parents when they bring them to the tests.

Nancy Segal: Sometimes.

Smadar Zmirin: Have you noticed anything changing in twin parenthood over the years?

Nancy Segal: It's hard to say. I've not really systematically recorded this, but I think that just anecdotally, I think parents are appreciating twinship a lot more, and it may just be the identicals. But I'm not sure I really can't speak to that. I know that there's a big push sort of towards identity and individuality. But I think you have to strike a happy balance with twins. I think they have to be individuals on their own, but they're part of a twin pair, and I think they should be allowed to nurture it and enjoy it as much as possible.

Smadar Zmirin: Yeah. Are you close with your sister?

Nancy Segal: Well, as I said, we are now, but as children I don't think we were very close. We had our own friends, and you know. Of course, sisters and siblings share certain things that you know friends can't, because you see your parents up close and all that sort of thing. So to that degree, sure. And we have some similar memories about things, although we have some different memories, too. But yeah, I think that, like many siblings, you. You grow closer in adulthood, particularly once your parents pass, you know, siblings your same age, so you tend to stay together and get closer.

Smadar Zmirin: Is there anything that you feel like as a personal experience or so from your work that you feel it is important for twin parents to know to foster better twin relationships for identical and fraternal? Because it may imply different strategies.

Nancy Segal: Well, I just think, you know, again paying attention to twin type is important, but it's not the overriding consideration.

And I think that that just you want to nurture each child to be the best that they can be.

I think that's it, not to force things on that they don't want.

you know, if twins are, if you have twins and one's invited to a party, the other one isn't, let the one go, and for the other twins range a special day or something like that.

But I think that you know you got to live real life and not everything happens. At the same time, we're together.

Smadar Zmirin: No, despite our best efforts, life doesn't really accommodate. And yeah.

Nancy Segal: I think that parents who have an older child, followed by twins have a rather difficult situation, because, you know, it's hard enough to be dethroned. But then, when you're dethroned by twins, it's really difficult, because everybody pays attention to twins. So you want to make sure that people pay attention to the older child when a single baby follows twins, that's easier because babies get attention. So that's not as difficult a situation.

Smadar Zmirin: Okay, that's really interesting. Yeah. And I've seen that usually the pairs I work with they either on their own or have an older sibling because I work with the very young ones. But it's really true, and I see it with the older toddlers that they are trying to get the attention as it is. But yeah, if you're a Singleton following twins, I can see how it might be a softer landing.

Nancy Segal: One of the saddest things I ever saw was a family that had an older girl, and then they had quadruplets, and they were invited to be on a television program. I was there, too. and they kept on telling the older girl to get off the stage. You know the producers, because they only wanted the quadruplets, and I mean my heart broke for this child.

Smadar Zmirin: Yeah, I mean talking about seeking attention and really, really starting to get it. That's true. Yeah.

And I want to ask you, Nancy, is there anything because you studied so many different domains in human behaviour and in twins? Is there? And you mentioned your next 2 books? Are there any areas that still puzzle you when it comes to twins or human behaviour, even though you studied it. Things that you feel like there is still more to it like we still need to know.

Nancy Segal: You know. I think there's 2 things. Well, a couple of things one is, we don't know what causes the fertilized egg to split, to create identical twins. We still don't know why that happens.

Secondly, I think a big area that's not studied at all for some reason is how twins decide to go to college together or apart.

You know what goes into all that no one really knows. There's lots of anecdotes, but no one has systematically done that, or made account of how many twins go to the same school? And if they do, do, they take different majors? Do they live together? These are all important things that nobody has ever tracked.

Smadar Zmirin: That's true. Yeah. I mean, I know, like anecdotally about different cases, about how the twins felt about it. But it's.

Nancy Segal: Right? Right? I I do, too. But there's so little there's nothing that's documented systematically, nothing.

Smadar Zmirin: And as far as your work, when a lot of the findings that you come across obviously are more relevant or less relevant depends on your age and your type of twin. Has anything came out of the findings in your studies that made you reflect on your choices in life that you think? Oh, maybe it's because of my thinking.

Nancy Segal: I'm, well, yeah, my sister was much more of a serious student early on than I was. I certainly am now, but and I was for many years, but she started out much more seriously involved in education than I did, and I think that I would have benefited if I had done the same thing. But you know you judge by results. I've had a great career, so I don't really have any regrets. But I think how would it have been different, I don't know.

And you know my sister got into a special high school in New York City. I didn't. I was chosen to take the exam. You had to be chosen to take it, but I didn't get in, and she did, and my parents very wisely let her go, but some parents at times have tried to get both kids in, even though only one did. And I'm glad my parents didn't do that. I would have felt rather sheepish if they tried to do something like that. So yeah, they just let us be as we were.

Smadar Zmirin: I mean, I can see there are advantages and disadvantages to either. But having worked with twins for this amount of years, I can really see the benefits of you know that freedom that your parents gave you and respected the fact that you are different, and you might be disappointed if you can't do exactly the same, but you are strong as an individual, and you will find your passion, and that's beautiful. They let you, really, you know, live your life to the fullest in that regard.

One of the things that I doubt there is much information about it, because it doesn't happen often, but I wonder if that's a topic of interest for you because I know you studied a bit, It's the identical twins marring identical twins and having kind or children who are cousins/siblings.

Is there any work done on those children? As far as their upbringing? I know there are not many cases. But is that something that you feel can be done?

Nancy Segal: Okay, we should. No one has studied, I mean, identical twins who marry identical twins. No one has studied the children. Really, there's a wonderful study that was done a long time ago on 50 such families, but they only studied the couples, not any of the children, but I think that would be of great interest. Now people do study the children that come from say, when one twin, when twins marry, they're both twins, but they marry unrelated people.

So then people look at the children there, and I have a study like that, too. But no one studied the children of the twins who marry twins, and of course they're full siblings genetically. So they're very interesting. I actually studied one family. I didn't really study them. I met a family once where the 2 mothers who had married the mothers were identical twins who married identical twins, and they had children on the same day, so they were kind of technically fraternal twins.

Smadar Zmirin: Yes, they would be, that's sure.

Nancy Segal: Very rare case. I don't know of any other one than that. I know. I'm gonna have to go soon. You know. Another 5 min or so, because I have tightly scheduled tonight.

Smadar Zmirin: That's absolutely fine. Yeah. But so, yeah, I guess for our closing question, is there anything that you feel that from your experience in the field, and also growing up as a twin, that you feel like twin parents should pay attention to, or main takeaways for their, you know, twin parenthood decision?

Nancy Segal: Well, I yeah, I think the most important thing is school separation. I think you have to be very careful with that. In the early grades. You want to make sure that both twins are happy with it, that the teachers are similar in certain ways, that one child won't be benefited. I mean, one problem I had was that my sister was put into a much nicer classroom, and that's a nicer teacher than I had.

So that was a big source of a problem. But I think that's important. And I think if twins want to be together, educators have to allow that the big push by educators is to put them in separate classes because they won't develop identities. They claim which is ridiculous. They certainly will. There's lots of clever things you can do like, put them in different play groups, put them in different tables. They can meet people that way and still have the security of their twin around.

So I think parents have to be very proactive when it comes to school separation. If they, if they disagree with what the school wants you got to say so.

Smadar Zmirin: Very, very wise. Yeah, wow, thank you so much. For your time today, Nancy, it's been very insightful and very interesting.

Nancy Segal: And I enjoyed it, too, and I'm glad I could help if I could. Yeah. And so let's stay in touch. And maybe if you come to California or I come to New Zealand, where in New Zealand are you?

Smadar Zmirin: I'm in Auckland.

Nancy Segal: In Auckland. Okay, yeah. Great. Yeah. I've been there. What's the city right across? There's a place right across from Auckland. I can't remember the name of it the South. No, it's something village, maybe, or…

Smadar Zmirin: Across from Auckland?

Nancy Segal: I thought so, or it's just very close to Auckland. Maybe I'm thinking of something else. I must be thinking something else all right. Never mind me.

Smadar Zmirin: Thank you so much, Nancy.

Nancy Segal: My pleasure. Stay in touch and we'll probably meet someday.

Smadar Zmirin: Yeah, I would love that.

Nancy Segal: Good. Okay. Bye-bye.

Smadar Zmirin: Bye.