Prodigy is a production of I Heart Radio. If you were raised by a different family, how different do you think you'd be, Would your personality be the same, would you have a different religion? Exactly how much does your DNA determine who you are? It's impossible to know, right or is it? My name is Lowell Berlante and this is Prodigy. One and seventy years ago, Gregor Mendel ran an experiment cross breeding pea plants for desirable traits and founded what would become the science of modern genetics. Mendel had discovered genes, the unit of inheritance passed down from parent to child. A hundred years after that, before we had the technology and knowledge that we have today, people wanted to know the answer to a basic but complicated question. Is our life and behavior dictated by genetics or environment? Nature versus nurture? It had to be some combination of both. But how could we untangle them in order to measure their effects. We needed to hold one constant so we can measure the other. If we could quantify one, we could deduce that effects unaccounted for were caused by the other. It's difficult and morally unethical to control a human being's genetics or environment. So how was it done the combination of ways. One was by studying adopted children. They grew up in completely different environments from their birth parents. Similarities to their birth parents were assumed to be inherited, while similarities to their adopted parrants were assumed to be environmental. The results of these adoption studies are then combined with twin studies. There's two types of twins, fraternal and identical. When to sperm fertilize two eggs, you get fraternal twins. They share fifty DNA and are equivalent to siblings. When one sperm fertilizes one egg and then splits, you get identical twins with identical DNA. Dr Robert Plowman is a geneticist and psychologist. He's been studying twins for over forty years and is one of the most sided psychologists of this century. Twin and adoption studies are the two main ways we used to use for a century to ask to what extent are the differences between people due to inherited DNA differences, nature or nurture. Doctor Nancy Siegel is an award winning geneticist and psychologist. I think we're interested in sending twins for two reasons. First is that there are beautiful natural experiment, very simple, very elegant that allows us to look at the genetic environmental influences on behavior simply by comparing identical twin similarities to fraternal twins similarities. I think the other reason why we're so taken with twins is linked to the fact that we all grow up expecting and learning about individual differences in behavior and in form and so when we encounter to people who look so much alike and act so much alike, it challenges our belief in the way the world works. Since fraternal and identical twin pairs are usually raised by the same parents in the same environment, we could compare how similar the pairs were to estimate if a trait was environmental or genetic. Since fraternal twins share DNA well identical twins share a DNA. If a trait was more often shared by identical twins, it was assumed to be genetic. Identical twins have matching DNA, so they're also a perfect phenomenon to measure the influence of the environment. Identical twins usually share an environment, so similarities could be environmental as well. But if the identical twins have completely different environments, then we could assume that similarities between the twins are genetic and differences are environmental. This is what's known as identical twins reared apart. The year was nineteen eighty and nineteen year old Bobby Shaffern had just arrived for his first day at Sullivan Community College in upstate New York. As he headed to his dorm room, he realized that students there were really nice to strangers. They greeted him as if he were an old friend. The weird thing was they kept calling him Eddie. My name is Bobby, he told them, but they just laughed. They thought he was joking, and he thought they were. Bobby found his room and was met by his new roommate, Michael Domets. Michael was confused and started asking Bobby questions, were you adopted? What's your birth date? Bobby looked very similar to his last roommate, Eddie, too similar, and Michael knew that Eddie wasn't returning to college that year. The two boys ran to the nearest pay phone and called Eddie, and when Michael put the phone to Bobby's ear, he heard his own voice. Bobby and Eddie were identical twins, separated at birth. They were strikingly similar and in many more ways than simply physical appearance. They were both wrestlers, They spoke the same, had the same birth mark, and even shared the same i Q score. Everyone was shocked, and the news quickly made its way to the local paper. The next day, they got a phone call from a young man named David. Turns out they actually weren't twins, they were triplets. This was the beginning of a media sensation that swept the nation. Triplets separated at birth and raised in different families with different socio economics data is The story is told in the documentary Three Identical Strangers. Another famous story is of the Gym Twins. They were adopted to different families in nineteen Both families named them James, but called them Jim. They both like carpentry, but dislike spelling. They both married a woman named Linda, then divorced and married a woman named Betty. They even both gave their son the same name, James Allen. They were both nail biters, got tension, headaches, and vacationed at the same beach in Florida. There's other interesting stories of identical twins reared apart, and they're all very similar. In nineteen seventy nine, a study began which analyzed one and thirty seven pairs of twins reared apart to determine the range of genetic effects. Doctor Nancy Siegel was a researcher in this study for nine years and was surprised by some of the behaviors that showed genetic influence, such as religion. We studied psychological measures, physiological, medical, I mean, just about everything that you could think of was in there. I think shoe side was the only thing we forgot about. After measuring nearly every possible metric, they concluded that identical twins raised apart are more similar to each other than fraternal twins raised together. Here's Dr Plowman, and the amazing thing is all psychological traits, including personality, are heritable, including once you might not expect to be like femininity, even attitudinal things. The first law behable genetics is everything is heritable. So twin of adoption studies are away for researchers to study nature and nurture. In n the largest ever collaborative biological project began. It costs two point seven billion dollars and took thirteen years, but in two thousand three it was completed successfully. We map the human genome and gained access to the source code of our own species. We discovered that each person consists of a ninety nine percent identical six billion letter genetic code, so the DNA difference between you, me, and Brad Pitt is point zero one. That slight difference in our code is called genetic variance, and it's part of what makes us unique. Each person has around five million of them. The variances exist when an individual has a different nucleotide in a DNA fragment, which is called a single nucleotide polymorphism. We abbreviate them as s n p S or snips. Polygenic means multiple genes, and apologenic score is a number that estimates the effect of multiple genetic variances on an individual's characteristics like weight or height or personality. We used to be that a single gene control these traits. Here's dr Pluman. We've learned that it's not one, or ten or a hundred DNA differences that make a difference for complex traits. What we're talking about is thousands of tiny DNA differences, and that's a real drag if you're a molecular biologist and you want to study pathways from genes to brain to behavior, Because if there's thousands of these DNA differences, they all have very small effects, so it's really difficult to trace any of those pathways. What you can do is put these together in a score. You can aggregate all these tiny DNA differences. That's what we call a polygenic score, and that can be useful for prediction. And that's the main thing I'm interested in, is making predictions about people's personality, cognitive abilities, and psychopathology. So instead of looking for a single gene responsible for something like i Q, we look at the smaller effects of a lot of them. This is what is known as a genome wide polygenic score. But sequencing a person's genome by itself doesn't give us much applicable information because we need something to compare it to. The larger our data set, the more relevant the information becomes. Observing the genetic variants in many individuals is known as a genome wide association study. They call it GAS. By analyzing the variances in a person's DNA and comparing it to many other people's DNA, we can learn what these variances do. One of my highest pologenetic scores is for body mass index weight. You know, it predicts about ten of the differences between people in weight. People say, well, if you knew you were at a genetic risk for being OBEs, you just give up and say, oh, well, I'm a genetic fatty. But it's not like that. You know, by knowing I have this genetic propensity, I know that I'm in a lifelong battle. I've sort of known that all before, but I'm always thinking, oh, it's these six pounds put on it Christmas. It's not you know, I put on weight more easily. It's harder for me to get rid of it. And I know all your skinny listeners are saying, just get a grip. If you don't eat so much, you won't get fat. Dr Robert Plowman has been researching behavioral genetics using twin and adoption studies for over forty years and has published over eight papers. His most recent book is titled Blueprint, How DNA Makes Us who we Are. It discusses the conclusions he's drawn from as many years of research. It took a long time to convince psychologists that genetics is important, about thirty years or so. But in the last ten years or so, the DNA revolution has come along, and a lot of psychologists still don't know about it because mostly it's happening in the medical area. But it's just as relevant to all psychological traits. I'd say in the next five years, psychologists an't going to know what hit them because you won't be able to do a study if you don't collect DNA. The book is considered somewhat controversial for it's forceful for trail of genetics as the dominant force in human behavior. For example, here's a quote. Parents matter, but they don't make a difference. Parents obviously matter tremendously in their children's lives. They provide the essential physical and psychological ingredients for children's development. But if genetics provides most of the systematic variants and environmental effects are unsystematic and unstable. This applies that parents don't make much of a difference in their children's outcomes beyond the genes they provide a conception end quote. So Dr Pluman's book received a reasonable amount of criticism, particularly for the idea that parents don't make a difference. We'll get into that after a quick break. Welcome back to Prodigy. So Blueprint has received some pretty strong criticism for the way it's message could be interpreted. In the later publication of the book, Dr Plullman included an afterward which said the most quoted phrase from Blueprint is parents matter, but they don't make a difference. The phrase don't make a difference is often misconstrued to mean can't make a difference. Don't make a difference means that differences in parenting as they exist in the populations we study do not make much of a difference in children's psychological outcomes. There was a view in Nature of my book. Nature is one of the big science journals, and it was a historian of science. He didn't speak to the data. He just basically said he didn't like the result. He's saying this is a return to determinism. And in my book I emphasized it's not fatalistic. It doesn't mean you can't do anything about it. Dr Plowman was talking about Nathaniel Comfort, a professor at Johns Hopkins University. So I got Professor Comfort on the phone to ask him about his position. Particularly, I'm interested in the social implications of thinking about genes too much, about an over emphasis on in A and genes and the kind of social impacts that it has, So I'm in no way anti genetics. I consider myself a friendly critic. Professor Comfort is a historian of biomedicine. He looks at messages like this in a historical context. To start by saying, Dr Plullman is a venerable, respected psychologist who has been working on these problems for many years, So I'm not really going to comment on his actual science. I'm more interested in the way that he's presenting his science to the public, which I think is honestly reckless and dangerous. I think it's also important to note here that although Dr Plullman had a large data set of ten thousand sets of twins, all of them were born in the UK over the course of twelve months and had parents who agreed to take part in the research, So all of the subjects are from a similar geographic and socio economic background. Study. You're talking about users from UK Biobank, which is in fact overwhelmingly white, middle class Britains, So the results from a study don't necessarily apply to African Americans, for example, or Hispanics or Asians. Dr Plullman wrote to me in an email that this study is applicable to the UK only, it can't be generalized beyond there. However, he seems not to include this important qualifier when making some pretty broad interpretations of his findings. Here's part of the review that Professor Comfort wrote about Dr Pluman's book in the Nature article quote. Although Plullman frequently uses more civil, progressive language than did his predecessors, the book's message is vintage genetic determinism. Plullman likes to say that various components of nurture matter, but they don't make a difference. But the benefits of good teaching, of school lunches and breakfasts, of having textbook and air conditioning and heating and plumbing have been established irrefutably, and they actually our causal. We know why stable blood sugar improves mental concentration. Yet Pluman dismisses such effects as unsystematic and unstable, so there's not much we can do about them. Ultimately, if unintentionally blueprint is a roadmap for regressive social policy. Nothing here seems overtly hostile to school children or anyone else, but Pluman's argument provides live ammunition for those who would abandon proven methods of improving academic achievement among socio economically deprived children. His utopia is a forensic world dictated by polygenic algorithms and the whims of those who know how to use them. People would be defined at birth by their DNA, expectations would be set, and opportunities, resources, and experiences would be doled out and withheld before anyone has had a chance to show their metal. To paraphrase Lewington in his nineteen seventy critique of Jensen's argument, Pluman has made it pretty clear what kind of world he wants. I oppose him, so that was a bit from the article. At first, I didn't understand Professor Comfort's critique and why Dr Pluman's work could possibly be interpreted as genetic determinism if you're not familiar with that term. It's the belief that our genetics are the dominant factor for our behavior. It's the extreme nature side of the debate and the cornerstone of the incredibly problematic theory of eugenics. Professor Comfort makes this point at the end of the article when he reverences Lewington's critique of Jensen. Arthur Jensen was a very controversial psychologist at Berkeley who argued that i Q is largely determined by jenes, so lower i Q scores from a particular group means inferior genetics, amongst other issues. This argument hinges on the idea that i Q tests are an accurate and universal measure of intelligence across populations. This kind of determinism tends to amount to a form of social Darwinism. Basically, Arrant's teachers, you don't matter, you know, when you turn everything into biology, or you make all your predictions based on biology or genetics, there's a risk of increasing stratification in society, of creating kind of biological casts. It'll continue the erosion of things like public education and public services that we've been seeing in recent decades. This just plays into the hands of people who are really trying to dissolve the social contract. But Dr Pluman rejects the idea that his book has a message of genetic determinism. He sees environmental effects as important but quote mostly random, unsystematic, and unstable, which means that we cannot do much about them. So I gave Dr Ploman the opportunity to respond to Professor Comfort in an email, and this is what he wrote. Quote. I find it hard to believe that a scientist is not aware of the twin and adoption data showing that inherited DNA differences are the major systematic source making us who we are as individuals. Why are identical twins reared apart almost as similar as identical twins reared together. Why to adopted children resemble their birth parents but not their adoptive parents for twins reared together? Why are identical twins twice as similar as non identical twins? Here's a quote from Blueprints afterward responding to Dr Comfort's article, The reviewer did not address the science of the book, He just didn't like what he misinterpreted as its message. I plead not guilty to this charge of genetic determinant them. Genetics is the main systematic force in shaping who we are as individuals, but genes are not destiny. In Blueprint, Dr Plowman says genetics is about the extent to which inherited DNA differences account for differences between people in other words, we can turn the television on or off as we please, but turning it off or leaving it on pleases individuals differently, in part due to genetic factors. Genetics is not a puppeteer pulling our strings. Genetic influences are probabilistic propensities, not predetermined programming. End quote. So I searched blueprint and found at least nine other occurrences where Pluman repeats that message. However, he also makes bold statements that seem to imply the opposite. For instance, the very first paragraph of the book states, quote, what would you think if you heard about a new fortune telling device that is touted to predict psychological traits like depression, schizophrenia, and school achievement. What's more, I can tell your fortune from the moment of your birth. It is completely reliable and unbiased, and it costs only one pounds. This might sound like yet another pop psychology claim about gimmicks that will change your life, but this one is in fact based on the best science of our times. The fortune teller is d n A. It's absolutely true that jenes matter just like environment matters. The way in which jans an environment interact differs from person to person, and we have no idea how that works. Dr Plowman also wrote, quote polygenic scores based on DNA rather than crystal balls, are fortune tellers. As we shall see. Prediction is crucial because it is the key to the prevention of psychological problems and the promotion of promise. End quote. I also gave Professor Comfort the opportunity to respond via email. He said quote, the vast majority of unshared environments have what Pluman calls random, unsystematic causes. That doesn't make unshared environments unimportant. It just means they're hard to study. Statistically, in human social behavior, few if any, direct lines can be drawn from cause to effect. We are shaped by subtle relationships, interacting variables, and big, unforeseeable events. The meaningful differences are individualized. Complex social behaviors are complex. Professor Plowman once called this a gloomy prospect, But it's only gloomy if you're a social psychologist, because it implies that your research is never going to explain very much. The prospect is not gloomy at all. Of your historian contingency, complexity and context or ur jam I can explain more about social behavior with a timeline than he can with an algorithm. There is no blueprint, Dr Pluman. There is no crystal ball. There's no ghost in the human machine. Of course, it just has so many parts, and those parts interact with such spectacularly idiosyncratic, adaptive, buffering, nonlinear variety that no statistical tool even begins to describe it. The blueprint is not just bad biology, it's socially dangerous. Historically, hackneyed metaphors for genetic determinism have misleadingly lent the authority of science to regressive social policies, from disadvantaging black and poor students to immigration restriction to coerced sterilization. Pologenic scores do not solve that problem. That's the end of the email. I want to wrap this debate by saying that I believe Dr Pluman has purely altruistic intentions. He's a brilliant and deservedly respected researcher. The problem is it's an extremely difficult subject to navigate, so it deserves a high level of critique. All right, we'll get into pologenic testing, epigenetics, and crisper right after this quick break. Here is Dr Zebo Wonderlick She studies gene expression at u C Irvine. She'd like to raise awareness about food and security on college campuses. You can find more info and donate at Basic Needs dot u C I dot E. DU doctor wanted to like raise some really interesting things we need to consider when studying genetics. The question is like, in terms of why we might want to figure out this genetics, I think a good question that human geneticists often brings up when they think about their work is to what end are we doing this work right? So if we figure it out, what does that imply for public policy or how people perceive their genetics? And so I guess the question is also like, even if we had some genetic component too, whether we would be good at chess or something like that, what would we use it for right, Because like I would assume that we could still you know, we want to live in a place where even if you're not genetically predisposed to be the best at something, that you could still do it right and that you would still have choice over because maybe you're really genetically pretty disposed to be excellent at something, but you don't like it. And so I think that that's you know, a question that People who work on human genetics often struggle with or wrestle with before designing their experiments, which is like, if I were to find a genetic component to XT, like, what would that imply for the human population. Another major concern is the privacy of your genetic information, because if you do genetic testing, UM, there's a high expectation that that information should be yours UM and to choose with whom you share it with. Right, So should your employer have access to that information? Like what if it influences their decision because your health care is going to be expensive or something like that. Because even though in an ideal world it's yours and it would be private, the reality is that it may not be all of the time. And then what does that imply for what could happen down the road if someone had access to that information. One of the best examples of this was the use of genetic genealogy to identify a man known as the Golden State Killer. He was responsible for at least thirteen murders and fifty rapes and had evaded capture for forty five years. While everyone is glad that the killer was caught, the way that he was is potentially alarming. One of his relatives had uploaded their genetic information to an open source database called g E D Match, which enabled investigators to identify a common ancestor. So not only does your genetic information become public if he used the database, people who never consented to it become public as well. Another interesting subject to consider is instead of dividing traits into two distinct categories of nature or nurture, maybe the environment influences how our genes are expressed. This is what's known as epigenetics. One way this works is by DNA methylation, which alter the expression of a DNA segment. A study was done by Michael Meaney and colleagues on the interaction between mother rats and their babies. Some mother rats groom their babies more often than others. These well groomed babies grow up to groom their babies more. The significant discovery was in the results of cross fostering. So when babies from low grooming mothers were given to the high grooming ones, they grew up to groom their babies more, and the opposite was also true. The effect took place in the expression of an estrogen receptor okay Let's shift focus to another emerging field of genetics. If you had the power to change anything about yourself, would you do it? And what would happen if everyone did? Because that's the question humanity is about to face. In Scientists first noticed an unusual repetitive DNAs equence when studying bacteria. However, there wasn't sufficient data at the time to predict what the function was. CRISPER stands for clustered regularly inner spaced short palindromic repeats. It uses a protein to edit DNA. Sixty years ago, computers were the size of an entire room. Now everyone has one, an order of magnitude more capable, and it fits in your pocket. We're still in the relatively early stages of gene editing, but make no mistake, this technology will change the world. We'll be able to do everything from cure diseases to create genetically superior embryos in vitro. Fertilization was criticized for creating life in a Patriot dish, but now it's commonplace, and we even genetically screen embryos for abnormalities. One step further would be to fix them. And while we're doing that, why not give them better eyesight and make them taller. Is there a line with shout and cross and if so, where is it? I spoke with Dr Dihan A. Taco. She's a postdoctoral scientist at London University Department of Experimental Medical Sciences. She uses Crisper to do research in neuroscience and stem cells. She's actually trying to figure out what makes us human. Human genome and the chimpanzee genome are almost identical, and when you look at the protein quoting genes, they're like of them are basically the same. So then the question is how come you know we and the chimpanzees are so different. You know, we're building countries and states and nations, but the chimpanzees are still using rudimentary tools in their daily life. Dr Ataco believes that the difference is in non coding RNA. She uses Crisper to stop their expression and then studies the effects. Crisper is really cool, but I was actually kind of concerned about some of the potential negative possibilities, specifically terrorists using it to create viruses. Yeah, I mean potentially they can crisper viruses. You can chrisper anything. It is quite expensive to do these experiments. I can't believe I'm going into this, but like it would have to be government run facilities that would have to be that can sponsor this. It's not just any you know group somewhere, So Crisper is not currently as accessible as I thought. It made life much easier for scientists, and it makes the work of scientists like her much quicker and cheaper to the taxpayer. But I was also concerned about it being a slippery slope eventually leading to designer babies, modifying embryos. It's considered a hard line because these changes are passed down to future generations. Changing in embryo is like changing the human race ethics aciety. It's incredibly risky because errors could result in new diseases. It's illegal in many countries, but no international standard for regulation currently exists. In fact, in two thousand eighteen, a Chinese scientist performed genets on embryos using Crisper in an attempt to improve HIV resistance. After the Chinese scandal, like a lot of politicians and policymakers as well as ethical boards of university, is kind of like woke up and we're like, okay, we need to regulate this better because no scientists, no matter how crazy we can be, wants to be associated with doing something that's unethical and mad. So, together with policy makers and ethics committees, you know, philosophers, etcetera, a lot of universities and loll countries are working together to make a comprehensive assessment of like, oh, where should we put the limit? What can we do? What can we not do? Crisper is a very exciting advancement that I feel very optimistic about. However, like the case with nuclear reactions, it also has the potential to do great harm and therefore needs to be carefully regulated by an international body. I want to wrap these first three episodes up with some sage advice on raising children. Instead of praising, like the achievement of being good at something, I praised the effort right for, like you work really hard to get to that point where you're good at this thing. Read to them, you know, take them outside, let them experience the world and let them make mistakes, encourage their abilities. Gently, read your kid well, listen to your kid. Your kid will probably tell you what he or she wants to do. There's only so many ten thou hours in a childhood, you know, so are you going to focus all of that and focus your relationship with your kid on that one thing? Whereas you know, I don't think that's a strategy as a parent, and nichoal listened to be the best that everything is it. The goal is to find out things you like to do. I'll finish with this quote from Dr Pluman's book Blueprint. Parenting is not a means to an end. It is a relationship, one of the longest lasting relationships in our lives. Just as with our partner and our friends, our relationship with our children should be based on loving them, not changing them. All right, So next week we'll be Christmas Eve when we have a very special bonus episode for you on the psychology of gift giving with Professor Jeff Gallack. I have so many questions to answer and a ton of really interesting topics to cover, So please subscribe to the show because I'll be back next week with another episode of Prodigy. Prodigy was created and produced by me loeweberl Ante. The apologetic score for Tyler Klang showed traits of an excellent eecutive producer. Music by Sebastian Phillips, covered by pam Peacock. Dr Robert Plowman is a respected and celebrated research professor at King's College in London. Definitely pick up a copy of his book Blueprint, How DNA Makes Us who we Are. Nathaniel Comfort is a professor at Johns Hopkins University and a talented writer. He's currently working on a biography of James Watson, who co discovered the double helix. Keep an eye out for it. Dr Nancy Siegel is an outstanding professor and the author of six books on twins. You can find more info at doctor Nancy Siegel Twins dot org. Dr Zebo wonder Like is a very kind professor at u C Irvine, where she studies gene expression. She wants to raise awareness about food and security on college campuses. You can find more info and donate at Basic Needs dot U C I dot e d U. Dr Dihan Ataco is a brilliant post doctoral researcher at Lone University doing very interesting research on what makes us human very special. Thanks to Dr Brian Collin and Camille des On. For more podcasts from My Heart Radio, visit the I Heart Radio app, Apple Podcasts, or wherever you get your podcasts,

Prodigy is a production of I Heart Radio. If you were raised by a different family, how different do you think you'd be, Would your personality be the same, would you have a different religion? Exactly how much does your DNA determine who you are? It's impossible to know, right or is it? My name is Lowell Berlante and this is Prodigy. One and seventy years ago, Gregor Mendel ran an experiment cross breeding pea plants for desirable traits and founded what would become the science of modern genetics. Mendel had discovered genes, the unit of inheritance passed down from parent to child. A hundred years after that, before we had the technology and knowledge that we have today, people wanted to know the answer to a basic but complicated question. Is our life and behavior dictated by genetics or environment? Nature versus nurture? It had to be some combination of both. But how could we untangle them in order to measure their effects. We needed to hold one constant so we can measure the other. If we could quantify one, we could deduce that effects unaccounted for were caused by the other. It's difficult and morally unethical to control a human being's genetics or environment. So how was it done the combination of ways. One was by studying adopted children. They grew up in completely different environments from their birth parents. Similarities to their birth parents were assumed to be inherited, while similarities to their adopted parrants were assumed to be environmental. The results of these adoption studies are then combined with twin studies. There's two types of twins, fraternal and identical. When to sperm fertilize two eggs, you get fraternal twins. They share fifty DNA and are equivalent to siblings. When one sperm fertilizes one egg and then splits, you get identical twins with identical DNA. Dr Robert Plowman is a geneticist and psychologist. He's been studying twins for over forty years and is one of the most sided psychologists of this century. Twin and adoption studies are the two main ways we used to use for a century to ask to what extent are the differences between people due to inherited DNA differences, nature or nurture. Doctor Nancy Siegel is an award winning geneticist and psychologist. I think we're interested in sending twins for two reasons. First is that there are beautiful natural experiment, very simple, very elegant that allows us to look at the genetic environmental influences on behavior simply by comparing identical twin similarities to fraternal twins similarities. I think the other reason why we're so taken with twins is linked to the fact that we all grow up expecting and learning about individual differences in behavior and in form and so when we encounter to people who look so much alike and act so much alike, it challenges our belief in the way the world works. Since fraternal and identical twin pairs are usually raised by the same parents in the same environment, we could compare how similar the pairs were to estimate if a trait was environmental or genetic. Since fraternal twins share DNA well identical twins share a DNA. If a trait was more often shared by identical twins, it was assumed to be genetic. Identical twins have matching DNA, so they're also a perfect phenomenon to measure the influence of the environment. Identical twins usually share an environment, so similarities could be environmental as well. But if the identical twins have completely different environments, then we could assume that similarities between the twins are genetic and differences are environmental. This is what's known as identical twins reared apart. The year was nineteen eighty and nineteen year old Bobby Shaffern had just arrived for his first day at Sullivan Community College in upstate New York. As he headed to his dorm room, he realized that students there were really nice to strangers. They greeted him as if he were an old friend. The weird thing was they kept calling him Eddie. My name is Bobby, he told them, but they just laughed. They thought he was joking, and he thought they were. Bobby found his room and was met by his new roommate, Michael Domets. Michael was confused and started asking Bobby questions, were you adopted? What's your birth date? Bobby looked very similar to his last roommate, Eddie, too similar, and Michael knew that Eddie wasn't returning to college that year. The two boys ran to the nearest pay phone and called Eddie, and when Michael put the phone to Bobby's ear, he heard his own voice. Bobby and Eddie were identical twins, separated at birth. They were strikingly similar and in many more ways than simply physical appearance. They were both wrestlers, They spoke the same, had the same birth mark, and even shared the same i Q score. Everyone was shocked, and the news quickly made its way to the local paper. The next day, they got a phone call from a young man named David. Turns out they actually weren't twins, they were triplets. This was the beginning of a media sensation that swept the nation. Triplets separated at birth and raised in different families with different socio economics data is The story is told in the documentary Three Identical Strangers. Another famous story is of the Gym Twins. They were adopted to different families in nineteen Both families named them James, but called them Jim. They both like carpentry, but dislike spelling. They both married a woman named Linda, then divorced and married a woman named Betty. They even both gave their son the same name, James Allen. They were both nail biters, got tension, headaches, and vacationed at the same beach in Florida. There's other interesting stories of identical twins reared apart, and they're all very similar. In nineteen seventy nine, a study began which analyzed one and thirty seven pairs of twins reared apart to determine the range of genetic effects. Doctor Nancy Siegel was a researcher in this study for nine years and was surprised by some of the behaviors that showed genetic influence, such as religion. We studied psychological measures, physiological, medical, I mean, just about everything that you could think of was in there. I think shoe side was the only thing we forgot about. After measuring nearly every possible metric, they concluded that identical twins raised apart are more similar to each other than fraternal twins raised together. Here's Dr Plowman, and the amazing thing is all psychological traits, including personality, are heritable, including once you might not expect to be like femininity, even attitudinal things. The first law behable genetics is everything is heritable. So twin of adoption studies are away for researchers to study nature and nurture. In n the largest ever collaborative biological project began. It costs two point seven billion dollars and took thirteen years, but in two thousand three it was completed successfully. We map the human genome and gained access to the source code of our own species. We discovered that each person consists of a ninety nine percent identical six billion letter genetic code, so the DNA difference between you, me, and Brad Pitt is point zero one. That slight difference in our code is called genetic variance, and it's part of what makes us unique. Each person has around five million of them. The variances exist when an individual has a different nucleotide in a DNA fragment, which is called a single nucleotide polymorphism. We abbreviate them as s n p S or snips. Polygenic means multiple genes, and apologenic score is a number that estimates the effect of multiple genetic variances on an individual's characteristics like weight or height or personality. We used to be that a single gene control these traits. Here's dr Pluman. We've learned that it's not one, or ten or a hundred DNA differences that make a difference for complex traits. What we're talking about is thousands of tiny DNA differences, and that's a real drag if you're a molecular biologist and you want to study pathways from genes to brain to behavior, Because if there's thousands of these DNA differences, they all have very small effects, so it's really difficult to trace any of those pathways. What you can do is put these together in a score. You can aggregate all these tiny DNA differences. That's what we call a polygenic score, and that can be useful for prediction. And that's the main thing I'm interested in, is making predictions about people's personality, cognitive abilities, and psychopathology. So instead of looking for a single gene responsible for something like i Q, we look at the smaller effects of a lot of them. This is what is known as a genome wide polygenic score. But sequencing a person's genome by itself doesn't give us much applicable information because we need something to compare it to. The larger our data set, the more relevant the information becomes. Observing the genetic variants in many individuals is known as a genome wide association study. They call it GAS. By analyzing the variances in a person's DNA and comparing it to many other people's DNA, we can learn what these variances do. One of my highest pologenetic scores is for body mass index weight. You know, it predicts about ten of the differences between people in weight. People say, well, if you knew you were at a genetic risk for being OBEs, you just give up and say, oh, well, I'm a genetic fatty. But it's not like that. You know, by knowing I have this genetic propensity, I know that I'm in a lifelong battle. I've sort of known that all before, but I'm always thinking, oh, it's these six pounds put on it Christmas. It's not you know, I put on weight more easily. It's harder for me to get rid of it. And I know all your skinny listeners are saying, just get a grip. If you don't eat so much, you won't get fat. Dr Robert Plowman has been researching behavioral genetics using twin and adoption studies for over forty years and has published over eight papers. His most recent book is titled Blueprint, How DNA Makes Us who we Are. It discusses the conclusions he's drawn from as many years of research. It took a long time to convince psychologists that genetics is important, about thirty years or so. But in the last ten years or so, the DNA revolution has come along, and a lot of psychologists still don't know about it because mostly it's happening in the medical area. But it's just as relevant to all psychological traits. I'd say in the next five years, psychologists an't going to know what hit them because you won't be able to do a study if you don't collect DNA. The book is considered somewhat controversial for it's forceful for trail of genetics as the dominant force in human behavior. For example, here's a quote. Parents matter, but they don't make a difference. Parents obviously matter tremendously in their children's lives. They provide the essential physical and psychological ingredients for children's development. But if genetics provides most of the systematic variants and environmental effects are unsystematic and unstable. This applies that parents don't make much of a difference in their children's outcomes beyond the genes they provide a conception end quote. So Dr Pluman's book received a reasonable amount of criticism, particularly for the idea that parents don't make a difference. We'll get into that after a quick break. Welcome back to Prodigy. So Blueprint has received some pretty strong criticism for the way it's message could be interpreted. In the later publication of the book, Dr Plullman included an afterward which said the most quoted phrase from Blueprint is parents matter, but they don't make a difference. The phrase don't make a difference is often misconstrued to mean can't make a difference. Don't make a difference means that differences in parenting as they exist in the populations we study do not make much of a difference in children's psychological outcomes. There was a view in Nature of my book. Nature is one of the big science journals, and it was a historian of science. He didn't speak to the data. He just basically said he didn't like the result. He's saying this is a return to determinism. And in my book I emphasized it's not fatalistic. It doesn't mean you can't do anything about it. Dr Plowman was talking about Nathaniel Comfort, a professor at Johns Hopkins University. So I got Professor Comfort on the phone to ask him about his position. Particularly, I'm interested in the social implications of thinking about genes too much, about an over emphasis on in A and genes and the kind of social impacts that it has, So I'm in no way anti genetics. I consider myself a friendly critic. Professor Comfort is a historian of biomedicine. He looks at messages like this in a historical context. To start by saying, Dr Plullman is a venerable, respected psychologist who has been working on these problems for many years, So I'm not really going to comment on his actual science. I'm more interested in the way that he's presenting his science to the public, which I think is honestly reckless and dangerous. I think it's also important to note here that although Dr Plullman had a large data set of ten thousand sets of twins, all of them were born in the UK over the course of twelve months and had parents who agreed to take part in the research, So all of the subjects are from a similar geographic and socio economic background. Study. You're talking about users from UK Biobank, which is in fact overwhelmingly white, middle class Britains, So the results from a study don't necessarily apply to African Americans, for example, or Hispanics or Asians. Dr Plullman wrote to me in an email that this study is applicable to the UK only, it can't be generalized beyond there. However, he seems not to include this important qualifier when making some pretty broad interpretations of his findings. Here's part of the review that Professor Comfort wrote about Dr Pluman's book in the Nature article quote. Although Plullman frequently uses more civil, progressive language than did his predecessors, the book's message is vintage genetic determinism. Plullman likes to say that various components of nurture matter, but they don't make a difference. But the benefits of good teaching, of school lunches and breakfasts, of having textbook and air conditioning and heating and plumbing have been established irrefutably, and they actually our causal. We know why stable blood sugar improves mental concentration. Yet Pluman dismisses such effects as unsystematic and unstable, so there's not much we can do about them. Ultimately, if unintentionally blueprint is a roadmap for regressive social policy. Nothing here seems overtly hostile to school children or anyone else, but Pluman's argument provides live ammunition for those who would abandon proven methods of improving academic achievement among socio economically deprived children. His utopia is a forensic world dictated by polygenic algorithms and the whims of those who know how to use them. People would be defined at birth by their DNA, expectations would be set, and opportunities, resources, and experiences would be doled out and withheld before anyone has had a chance to show their metal. To paraphrase Lewington in his nineteen seventy critique of Jensen's argument, Pluman has made it pretty clear what kind of world he wants. I oppose him, so that was a bit from the article. At first, I didn't understand Professor Comfort's critique and why Dr Pluman's work could possibly be interpreted as genetic determinism if you're not familiar with that term. It's the belief that our genetics are the dominant factor for our behavior. It's the extreme nature side of the debate and the cornerstone of the incredibly problematic theory of eugenics. Professor Comfort makes this point at the end of the article when he reverences Lewington's critique of Jensen. Arthur Jensen was a very controversial psychologist at Berkeley who argued that i Q is largely determined by jenes, so lower i Q scores from a particular group means inferior genetics, amongst other issues. This argument hinges on the idea that i Q tests are an accurate and universal measure of intelligence across populations. This kind of determinism tends to amount to a form of social Darwinism. Basically, Arrant's teachers, you don't matter, you know, when you turn everything into biology, or you make all your predictions based on biology or genetics, there's a risk of increasing stratification in society, of creating kind of biological casts. It'll continue the erosion of things like public education and public services that we've been seeing in recent decades. This just plays into the hands of people who are really trying to dissolve the social contract. But Dr Pluman rejects the idea that his book has a message of genetic determinism. He sees environmental effects as important but quote mostly random, unsystematic, and unstable, which means that we cannot do much about them. So I gave Dr Ploman the opportunity to respond to Professor Comfort in an email, and this is what he wrote. Quote. I find it hard to believe that a scientist is not aware of the twin and adoption data showing that inherited DNA differences are the major systematic source making us who we are as individuals. Why are identical twins reared apart almost as similar as identical twins reared together. Why to adopted children resemble their birth parents but not their adoptive parents for twins reared together? Why are identical twins twice as similar as non identical twins? Here's a quote from Blueprints afterward responding to Dr Comfort's article, The reviewer did not address the science of the book, He just didn't like what he misinterpreted as its message. I plead not guilty to this charge of genetic determinant them. Genetics is the main systematic force in shaping who we are as individuals, but genes are not destiny. In Blueprint, Dr Plowman says genetics is about the extent to which inherited DNA differences account for differences between people in other words, we can turn the television on or off as we please, but turning it off or leaving it on pleases individuals differently, in part due to genetic factors. Genetics is not a puppeteer pulling our strings. Genetic influences are probabilistic propensities, not predetermined programming. End quote. So I searched blueprint and found at least nine other occurrences where Pluman repeats that message. However, he also makes bold statements that seem to imply the opposite. For instance, the very first paragraph of the book states, quote, what would you think if you heard about a new fortune telling device that is touted to predict psychological traits like depression, schizophrenia, and school achievement. What's more, I can tell your fortune from the moment of your birth. It is completely reliable and unbiased, and it costs only one pounds. This might sound like yet another pop psychology claim about gimmicks that will change your life, but this one is in fact based on the best science of our times. The fortune teller is d n A. It's absolutely true that jenes matter just like environment matters. The way in which jans an environment interact differs from person to person, and we have no idea how that works. Dr Plowman also wrote, quote polygenic scores based on DNA rather than crystal balls, are fortune tellers. As we shall see. Prediction is crucial because it is the key to the prevention of psychological problems and the promotion of promise. End quote. I also gave Professor Comfort the opportunity to respond via email. He said quote, the vast majority of unshared environments have what Pluman calls random, unsystematic causes. That doesn't make unshared environments unimportant. It just means they're hard to study. Statistically, in human social behavior, few if any, direct lines can be drawn from cause to effect. We are shaped by subtle relationships, interacting variables, and big, unforeseeable events. The meaningful differences are individualized. Complex social behaviors are complex. Professor Plowman once called this a gloomy prospect, But it's only gloomy if you're a social psychologist, because it implies that your research is never going to explain very much. The prospect is not gloomy at all. Of your historian contingency, complexity and context or ur jam I can explain more about social behavior with a timeline than he can with an algorithm. There is no blueprint, Dr Pluman. There is no crystal ball. There's no ghost in the human machine. Of course, it just has so many parts, and those parts interact with such spectacularly idiosyncratic, adaptive, buffering, nonlinear variety that no statistical tool even begins to describe it. The blueprint is not just bad biology, it's socially dangerous. Historically, hackneyed metaphors for genetic determinism have misleadingly lent the authority of science to regressive social policies, from disadvantaging black and poor students to immigration restriction to coerced sterilization. Pologenic scores do not solve that problem. That's the end of the email. I want to wrap this debate by saying that I believe Dr Pluman has purely altruistic intentions. He's a brilliant and deservedly respected researcher. The problem is it's an extremely difficult subject to navigate, so it deserves a high level of critique. All right, we'll get into pologenic testing, epigenetics, and crisper right after this quick break. Here is Dr Zebo Wonderlick She studies gene expression at u C Irvine. She'd like to raise awareness about food and security on college campuses. You can find more info and donate at Basic Needs dot u C I dot E. DU doctor wanted to like raise some really interesting things we need to consider when studying genetics. The question is like, in terms of why we might want to figure out this genetics, I think a good question that human geneticists often brings up when they think about their work is to what end are we doing this work right? So if we figure it out, what does that imply for public policy or how people perceive their genetics? And so I guess the question is also like, even if we had some genetic component too, whether we would be good at chess or something like that, what would we use it for right, Because like I would assume that we could still you know, we want to live in a place where even if you're not genetically predisposed to be the best at something, that you could still do it right and that you would still have choice over because maybe you're really genetically pretty disposed to be excellent at something, but you don't like it. And so I think that that's you know, a question that People who work on human genetics often struggle with or wrestle with before designing their experiments, which is like, if I were to find a genetic component to XT, like, what would that imply for the human population. Another major concern is the privacy of your genetic information, because if you do genetic testing, UM, there's a high expectation that that information should be yours UM and to choose with whom you share it with. Right, So should your employer have access to that information? Like what if it influences their decision because your health care is going to be expensive or something like that. Because even though in an ideal world it's yours and it would be private, the reality is that it may not be all of the time. And then what does that imply for what could happen down the road if someone had access to that information. One of the best examples of this was the use of genetic genealogy to identify a man known as the Golden State Killer. He was responsible for at least thirteen murders and fifty rapes and had evaded capture for forty five years. While everyone is glad that the killer was caught, the way that he was is potentially alarming. One of his relatives had uploaded their genetic information to an open source database called g E D Match, which enabled investigators to identify a common ancestor. So not only does your genetic information become public if he used the database, people who never consented to it become public as well. Another interesting subject to consider is instead of dividing traits into two distinct categories of nature or nurture, maybe the environment influences how our genes are expressed. This is what's known as epigenetics. One way this works is by DNA methylation, which alter the expression of a DNA segment. A study was done by Michael Meaney and colleagues on the interaction between mother rats and their babies. Some mother rats groom their babies more often than others. These well groomed babies grow up to groom their babies more. The significant discovery was in the results of cross fostering. So when babies from low grooming mothers were given to the high grooming ones, they grew up to groom their babies more, and the opposite was also true. The effect took place in the expression of an estrogen receptor okay Let's shift focus to another emerging field of genetics. If you had the power to change anything about yourself, would you do it? And what would happen if everyone did? Because that's the question humanity is about to face. In Scientists first noticed an unusual repetitive DNAs equence when studying bacteria. However, there wasn't sufficient data at the time to predict what the function was. CRISPER stands for clustered regularly inner spaced short palindromic repeats. It uses a protein to edit DNA. Sixty years ago, computers were the size of an entire room. Now everyone has one, an order of magnitude more capable, and it fits in your pocket. We're still in the relatively early stages of gene editing, but make no mistake, this technology will change the world. We'll be able to do everything from cure diseases to create genetically superior embryos in vitro. Fertilization was criticized for creating life in a Patriot dish, but now it's commonplace, and we even genetically screen embryos for abnormalities. One step further would be to fix them. And while we're doing that, why not give them better eyesight and make them taller. Is there a line with shout and cross and if so, where is it? I spoke with Dr Dihan A. Taco. She's a postdoctoral scientist at London University Department of Experimental Medical Sciences. She uses Crisper to do research in neuroscience and stem cells. She's actually trying to figure out what makes us human. Human genome and the chimpanzee genome are almost identical, and when you look at the protein quoting genes, they're like of them are basically the same. So then the question is how come you know we and the chimpanzees are so different. You know, we're building countries and states and nations, but the chimpanzees are still using rudimentary tools in their daily life. Dr Ataco believes that the difference is in non coding RNA. She uses Crisper to stop their expression and then studies the effects. Crisper is really cool, but I was actually kind of concerned about some of the potential negative possibilities, specifically terrorists using it to create viruses. Yeah, I mean potentially they can crisper viruses. You can chrisper anything. It is quite expensive to do these experiments. I can't believe I'm going into this, but like it would have to be government run facilities that would have to be that can sponsor this. It's not just any you know group somewhere, So Crisper is not currently as accessible as I thought. It made life much easier for scientists, and it makes the work of scientists like her much quicker and cheaper to the taxpayer. But I was also concerned about it being a slippery slope eventually leading to designer babies, modifying embryos. It's considered a hard line because these changes are passed down to future generations. Changing in embryo is like changing the human race ethics aciety. It's incredibly risky because errors could result in new diseases. It's illegal in many countries, but no international standard for regulation currently exists. In fact, in two thousand eighteen, a Chinese scientist performed genets on embryos using Crisper in an attempt to improve HIV resistance. After the Chinese scandal, like a lot of politicians and policymakers as well as ethical boards of university, is kind of like woke up and we're like, okay, we need to regulate this better because no scientists, no matter how crazy we can be, wants to be associated with doing something that's unethical and mad. So, together with policy makers and ethics committees, you know, philosophers, etcetera, a lot of universities and loll countries are working together to make a comprehensive assessment of like, oh, where should we put the limit? What can we do? What can we not do? Crisper is a very exciting advancement that I feel very optimistic about. However, like the case with nuclear reactions, it also has the potential to do great harm and therefore needs to be carefully regulated by an international body. I want to wrap these first three episodes up with some sage advice on raising children. Instead of praising, like the achievement of being good at something, I praised the effort right for, like you work really hard to get to that point where you're good at this thing. Read to them, you know, take them outside, let them experience the world and let them make mistakes, encourage their abilities. Gently, read your kid well, listen to your kid. Your kid will probably tell you what he or she wants to do. There's only so many ten thou hours in a childhood, you know, so are you going to focus all of that and focus your relationship with your kid on that one thing? Whereas you know, I don't think that's a strategy as a parent, and nichoal listened to be the best that everything is it. The goal is to find out things you like to do. I'll finish with this quote from Dr Pluman's book Blueprint. Parenting is not a means to an end. It is a relationship, one of the longest lasting relationships in our lives. Just as with our partner and our friends, our relationship with our children should be based on loving them, not changing them. All right, So next week we'll be Christmas Eve when we have a very special bonus episode for you on the psychology of gift giving with Professor Jeff Gallack. I have so many questions to answer and a ton of really interesting topics to cover, So please subscribe to the show because I'll be back next week with another episode of Prodigy. Prodigy was created and produced by me loeweberl Ante. The apologetic score for Tyler Klang showed traits of an excellent eecutive producer. Music by Sebastian Phillips, covered by pam Peacock. Dr Robert Plowman is a respected and celebrated research professor at King's College in London. Definitely pick up a copy of his book Blueprint, How DNA Makes Us who we Are. Nathaniel Comfort is a professor at Johns Hopkins University and a talented writer. He's currently working on a biography of James Watson, who co discovered the double helix. Keep an eye out for it. Dr Nancy Siegel is an outstanding professor and the author of six books on twins. You can find more info at doctor Nancy Siegel Twins dot org. Dr Zebo wonder Like is a very kind professor at u C Irvine, where she studies gene expression. She wants to raise awareness about food and security on college campuses. You can find more info and donate at Basic Needs dot U C I dot e d U. Dr Dihan Ataco is a brilliant post doctoral researcher at Lone University doing very interesting research on what makes us human very special. Thanks to Dr Brian Collin and Camille des On. For more podcasts from My Heart Radio, visit the I Heart Radio app, Apple Podcasts, or wherever you get your podcasts,