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

27:56You 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 than alternative ways. Yeah, I fear that there's an unseen twin out there of me doing all of the embarrassing shit that I do privately and letting other people know about it.

28:31I'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? So how many tattoos have you got? But they're very discreet individual examples that explain an entire suite of traits that somebody has. 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.

29:14What 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.

29:50I 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 that won't be focused on it. So for example, I did something with names in that Japanese journal twins how often they name their children the same name and we lead 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 there 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.

30:28They lived only 40 miles apart in Ohio and they used to bite their 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 block strip of beach in Florida, amazing they never met. They had numerous similarities and they named their sons James Allen and James Allen. One Allen had a two else one had one. You can laugh about that but why would you name what goes into name picking? Obviously the other partner has a saying as two 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 Allen reminded of somebody like the way it sounded.

31:17I 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 Jim twins married Betty and divorced her married Linda, divorced her married Sandy. Now the other one also married Sandy divorce to her married Linda. If I were Linda, I'd be a little nervous because Betty's coming around and going, you came into the atmosphere. I'd probably go running. So interesting. And again, you know, 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 you've been raised apart, different books that we read, different whatever, whatever, whatever.

32:09And yeah. They read the same, they read similar books in the reads apart. Well, there we go. But it's just, it's this permanent gravitational pull towards your predisposition. I think so. You know, we all have choices in 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.

32:47And 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.

33:20Very little genetic effect when you're young at home starts to kick in when you become an adolescent. Does IQ is 0 .8 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 deniers 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.

34:00all 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 partner or raised together. But again, I certainly would nutrition, I mean, one twin is exposed to a condition other one isn't. There are cases where one had COVID one didn't, that sort of thing.

34:38So 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 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 were still a Markleby 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. You know, she wanted her now brother to be happy and content, and the brother wasn't for many, many years.

35:18What 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 that virtually everything you rattled off. schizophrenia is about 40 to 50%. It's nowhere near one. The one that the only psychopathologist is really the strongest genetic effect I've seen is autism at about 70%. That can also vary depending on whether you strict or lose your criteria. But bipolar disorder has a genetic effect.

36:02Dimension breast cancer interestingly does not. It's about 20 % similarity in females. Wow, so you could have 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, so this and 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.

36:39And 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.

37:18But body mass index, BMI, does have a genetic effect as does height and weight separately. Yeah, 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? Correlation. Correlation, that's it. 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's because of their lifestyle, you know, look at look at this, but there's a huge genetic component to people's weight And you don't know how I had Robert Ployman on the show.

38:08He 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 It's just so alluring and he told me this thing and he said there are many ways to get fat But 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 released in your stomach.

38:43It might be that you comfort eat because of the way that your mental dysfunction is. It may be that you really don't like exercise. You are low on energy. Maybe 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 route, 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 In fact 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?

39:25How 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 are adoption studies twins raised apart. You want to disentangle the genes of the environment. That's what you want to do many develop mental psychologist 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.

39:59Well, how would I know which 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.

40:37But the point being that when you see particular I have a friend here in Austin, Aubrey Marcus, the guy that founded on it. 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, it's not, 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, it's not a particular surprise that in adulthood, you had a very high bar for yourself.

41:18Super 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, you know within the Setting that they find themselves in it's not There's so many majors we could all be right?

42:02The 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 a... And I have no interest in being a lawyer. My sister, my twin sister is a lawyer, but I have no interest in it. Is the, 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 have born in cesarean section and what happens to be a minute old and the other, I think to make a big deal over that means nothing.

42:49Now, 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 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. It's ridiculous. Is there anything that you can learn from triplets that you can't learn from twins?

43:28It 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 identicles 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 identical, you know, I mean, it's basically three pairs of twins so you can match everybody up every 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.

44:06And 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 identical. And I would feel 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. Interesting. 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 know, 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.

44:52So 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 secret study that followed these children up until the age of 12, that telling them or their parents that they had a twin.

45:28So 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.

46:03And 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 20 children who are 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 they be gives the other one away later or or they're brought together to an orphanage and then somehow they're separated because people don't realize their twins or whatever.

46:38But 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 in part, 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.

47:07And 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 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. I have. It's amazing. It's the most wonderful experience you could ever imagine. And twins do different things.

47:44Some jump up and down, some hug and kiss, some just kind of look at each other. Sometimes 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 tell if you 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?

48:18Would you go look for them? Well, modest interest. How about 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.

48:58I will say that some traits are harder to change than others, 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 genes don't tell you what to do. You're 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 -sell movement that William in particular studies.

49:43You 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 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 exor -y or Zed.

50:21Yeah. 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. You know, it makes us predisposed 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.

50:57So 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? Well, 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.

51:38They 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.

52:13How much? I'm just mentioning. 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 you know, 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.

52:58Thinking 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 I think that's a great responsibility.

53:46You know, 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 the good parenting is really sensitivity to the child and being very supportive and nurtured. 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? Jeffrey Miller once tweeted that every parenting book combined is less useful than one book on behavioral genetics for parents to read.

54:23I think it's very well put. I would agree with that. Yeah. It's just, I try and look back. 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. Obviously, all children will change parents, it's a massive life switch.

55:05But yeah, it's a, 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, you know, 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.

55:51Yes, 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. That's a lovely insight.

56:23And I think when I first spoke to Polo and 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 parent's 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. I know no forms about saying that. Yeah, I think so too. And there is, in a meritocracy, if you are your successes, then it also means that you are your losses too, right?

57:10And we know that people have very different, and 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 each of us 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 momming your way to hope that you can create a 140 IQ child I it's right you're gonna be disappointed keep 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 got a bit child with absolutely no interest in that whatsoever because the genes Re -shockle in every generation and and then also what's popular in one generation may not be popular in another I need if a child has a certain ability to align with that of the parents.

58:10There may be something else that's grabbed me in everybody's attention in the generation to which the child is born. So these things have all kinds of factors affecting them. Parents and children I think 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 and 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.

58:46And 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 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.

59:22but 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, 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 count for a lot. You know what it makes me think about.

1:00:01I 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 it 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.

1:00:41And there's a real interest in that now too. So 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 I said it appeared 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 from New Jersey moved to LA was an aspiring actress put a video of herself online A friend of the other twins 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.

1:01:44Now 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.

1:02:23And 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. And 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.

1:03:04Did 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.

1:03:42Many 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 for Trinnell 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 interracial couples and then the children that they have.

1:04:27I'm doing a study on that, but keep going. Okay. All right. So my bro science, not your real science, we can get onto 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 you know, the gene is relatively dominant. and 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.

1:05:08And 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 byracial twins too 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 And they told me that their life experiences were extremely different despite being raised at home in the same communities.

1:05:57Everybody thought that the one who looked Hispanic was the 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 and 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.

1:06:42Yeah, 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, it, 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.

1:07:28And I think people, 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 pools, different protocols, conversion of 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 rid of 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 .75 is the genetic effect, and it's rare to get that kind of repetition, replication, I should say, in the behavioral science.

1:08:31It'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 of those. Lots of replication there and lots of converging evidence. And I really love that because 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.

1:09:12There's a wonderful study done in the 50s where they simply asked twins, you know, who would you miss most in the event of death, twin mother and 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? It really wasn't interpretation. It was a sociological study. It was mainly to see what if, what is out there.

1:09:48They really didn't have an interpretation. It was basically what if. But the white -air aligns with the average genetic and evolutionary psychological interpretations. That's right, it does. Which is why we're interested in it. You mentioned that, you've 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've ranked 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.

1:10:29Yep for more identicals and fraternals Plum and study is twins raised together and he has thousands of pairs so definitely gonna have more yeah I think it was every Every set of twins born in the UK between like 1991 and 1994 or something right? It's 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 with 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 conferences which are held every two years, I organized a film session where I showed films about different aspects of twinship.

1:11:11And 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, these 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 Is this the one I think it's more the identical twin men and they had a secret Is this the one?

1:11:54Yeah, they have a secret. They 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 didn't 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 of your book, awesome, awesome breakdown of this, and then that that tell me who I am is harrowing. And 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.

1:12:33And yeah, on this tell me who I you see these guys reveal this lifelong secret to each other. Yeah. On set. Yeah. And it's the first time it ever happened. It is. Yeah. 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 Adopted Agency that I think is also excellent called the Twinting 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 changes. Also very excellent and many of the twins are in both films.

1:13:10You 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 where they're 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 for Trinos were so different.

1:13:46It 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 International 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 it costed me to one side and I've been looking forward to speaking to you for ages and I'm super, super excited to see what you do next.

1:14:22Where should people go if they're interested in the work that you're doing, what books should did they start with and what ones of you are coming out and all the rest of it? Yeah. I have a website with one of my twin books and one of my related material. And that is Dr. DR Nancy Segel, so DRNA and CYSEGAL twins .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 Gatefather's twin sons. The citizenship case, the capture of the world. They might want to look at my photo book on the Holocaust twins. There's a lot of interesting stories about twinship in there.

1:15:01And 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 Intwine 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, long -for -death, injury, custody, all kinds of things like that. Very, very fascinating. And right now, I'm going to 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.

1:15:48So I'm excited about that. 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 cost you.