Behavioral Genetics Robert Plomin

Summary

Highlights

• Plomin emphasizes that DNA differences account for nearly half of behavioral differences, challenging the environment-focused views of traditional psychology. 🧬
• Twin and adoption studies underscore the heritability of traits, from cognitive abilities to mental health issues. 👥
• Genetic influences are observed in various environmental experiences, reshaping how psychologists view environmental measures. 🌍
• There's a push towards finding specific genes to enhance predictive accuracy and preemptive care in psychology. 🔍
• Behavioral genetics is redefining our understanding of individual differences and the nature-versus-nurture debate. 🌟

Key Takeaways

• Behavioral genetics explores how DNA differences influence behavioral variations, challenging traditional views focused solely on the environment. 🧬
• Twin and adoption studies reveal that almost every trait is heritable, showing the substantial impact of genetics. 👯‍♂️
• Understanding the interplay between genes and environment can reshape our approach to psychology and mental health. 🔄
• Identifying specific genes can revolutionize psychological predictions, allowing for preemptive interventions. 🔍
• The genetic perspective is essential for understanding individual differences and can transform psychological practices. 🌟

Overview

Chapters

• 00:00 - 00:30: Introduction to Behavioral Genetics In the chapter 'Introduction to Behavioral Genetics,' the focus is on understanding the genetic influences that contribute to behavioral differences among individuals. The narrator is interested in exploring why certain people, for example, develop schizophrenia or reading disabilities. Traditionally, psychology emphasized the role of the environment, particularly parental influence during early childhood, in shaping behavior. However, this chapter delves into the genetic factors that also play a significant role in determining behavioral traits and differences.
• 00:30 - 01:00: Importance of DNA in Psychological Differences The chapter discusses the significant impact of DNA differences on psychological differences among people. It highlights that DNA accounts for nearly half of the variations in psychological traits, which is more significant than the combined effects of other psychological factors. The chapter emphasizes the importance of genetics in various areas of psychology, including mental health and illness.
• 01:00 - 01:30: Nature and Nurture Controversy The chapter delves into the longstanding debate in psychology surrounding 'nature vs. nurture.' This controversy considers whether genetics (nature) or environment (nurture) plays a more significant role in shaping cognitive abilities, personality, and school achievement. Historically, a strong emphasis was placed on nurture, attributing all aspects of human behavior and development to environmental factors. However, the advent of behavioral genetics a century ago, utilizing twin and adoption studies, began shifting the focus towards the importance of genetic influences.
• 01:30 - 02:00: Twin and Adoption Studies The chapter focuses on twin and adoption studies, discussing the twin method pioneered in the early 1900s, mainly in England and other parts of Europe. The method involves comparing monozygotic (identical) twins, who are genetic clones with identical DNA, as they arise from one fertilized egg. Identical twins account for approximately one-third of the 1% of births worldwide that are twin births.
• 02:00 - 03:00: Findings from Twin Studies The chapter 'Findings from Twin Studies' discusses the distinction between two types of twins: identical (monozygotic) and non-identical (dizygotic). It explains that dizygotic twins, making up two-thirds of all twin births, are genetically similar to regular siblings but share the womb at the same time. The chapter highlights how twin studies use these two groups to understand genetic influences on traits, such as musical ability. By comparing the traits in identical versus non-identical twins, researchers can infer the extent to which genetics play a role, treating it like a natural biological experiment.
• 03:00 - 04:00: Twin and Adoption Studies: Effects on Psychology The chapter explores the influence of genetics on individual differences, citing a survey encompassing 15 million twin studies across 4,000 papers. Findings suggest that everything, not just in psychology but also in physiology, including bone length and density, is influenced by inherited DNA differences.
• 04:00 - 05:00: Environmental Measures and Genetic Influence This chapter discusses the twin and adoption methods for studying the influences of environment and genetics. The twin method is likened to a biological experiment, while the adoption method is compared to a social experiment. The concept that both nature and nurture contribute to familial traits is explored. The chapter also touches on how past psychological theories attributed schizophrenia solely to environmental causes, like parental influence, while disregarding genetic factors.
• 05:00 - 06:00: Cognitive Abilities and Genetic Influence The chapter discusses the genetic and environmental influences on cognitive abilities. It highlights a study methodology using adoption cases, where children are separated from their genetic parents at birth and placed with adoptive parents. The genetic parents contribute the genes, while the adoptive parents provide the environment. This setup allows for a powerful test of genetic versus environmental influence based on the similarity between adopted children and their genetic versus adoptive parents. The prediction is that similarities with genetic parents reflect genetic factors.
• 06:00 - 08:00: Language Development and Genetic Influence This chapter explores the impact of genetics on language development by examining relationships between children and their biological and adoptive parents.
• 08:00 - 09:00: Behavioral Genetics Focus and DNA Differences The chapter discusses the field of behavioral genetics, emphasizing the shift from the belief that nothing is heritable to understanding that everything is heritable. It highlights recent techniques used to investigate when genetic influences manifest in development. Moreover, it discusses the complex interplay between nature and nurture, and provides an example involving the use of numerous environmental measures utilized in social sciences to study these interactions.
• 09:00 - 10:00: Genetic Influence in Psychology The concept of genetic influence in psychology is explored, particularly how traditional environmental measures also show significant genetic influences. This challenges the assumption that environmental factors are solely external and highlights the genetic component inherent in these psychological traits and life events.
• 10:00 - 11:00: Multivariate Approach in Psychopathology Psychology's approach to understanding the environment is shifting from seeing it as external circumstances to viewing it as experiences we undergo. Rather than being passive recipients of life's events, individuals actively participate in experiences such as financial disruptions and interpersonal conflicts. These aren't just external occurrences but are deeply intertwined with personal actions and reactions.
• 11:00 - 12:00: Interaction of Genes and Environment The chapter delves into the intricate relationship between genes and the environment. It highlights how the understanding of genetics has evolved and influenced the perception of environmental factors. A key principle discussed is the correlation between genetic functioning and environmental interaction. The chapter emphasizes the role of environment in gene expression, using cognitive abilities as an example. Vocabulary is pointed out as the most heritable measure of cognitive ability, illustrating the genetic perspective on environmental interaction.
• 12:00 - 13:00: Finding Genes and Molecular Genetics The chapter 'Finding Genes and Molecular Genetics' explores genetic predisposition to language use and vocabulary. It discusses how some people have a large vocabulary while others don't, emphasizing that vocabulary is not directly inherited through DNA due to the diversity of languages. Rather, language use is influenced by cognitive awareness of language subtleties. An example is given of two grandchildren: one is curious about word nuances and constantly questions meanings, while the other is more indifferent, reflecting varied approaches to language and cognition.
• 13:00 - 14:00: Prevention of Problems through Genetic Predictions The chapter delves into the concept of how genes influence individual behavior and development by interacting with the environment. It highlights how people's surroundings, such as social circles with intellectual interests, can impact development. The discussion incorporates the idea that genetic predispositions are expressed in conjunction with environmental factors, alongside examples like Einstein's late onset of speech, suggesting variability in developmental milestones due to genetic and environmental interactions.

Behavioral Genetics Robert Plomin Transcription

• 00:00 - 00:30 my interest is in behavioral genetics it's looking for genetic influences on why people differ in Behavior so some people become schizophrenic some children have reading disability so I'm interested in what causes those differences and for a century in Psychology people assumed all that's important is the environment and especially the environment your parent par provided in the first few years of
• 00:30 - 01:00 life that's from Freud onward but what we've learned using behavioral genetics is that DNA differences between people account for almost half of the differences between people this is far bigger than all the other effects in Psychology put together so not only does uh genetics matter it matters a lot for almost all areas of psychology mental health and illness
• 01:00 - 01:30 cognitive abilities personality School achievement we call nature is genetics nurture is environment so this is the longest standing controversy in Psychology nature and nurture for a long time people thought everything that we are is due to nurture we've shown that nature genetics is very important this goes back a hundred years or so when the first behavioral genetic techniques were developed twin studies and adoption studies the first ones were done in the
• 01:30 - 02:00 early 1900s primarily in England but also in other countries of Europe and the twin method involves um comparing two types of twins 1% of all births around the world are twins onethird of those are identical twins they're called monozygotic because they're one fertilized egg a zygote that they're like clones of one another they have the same DNA
• 02:00 - 02:30 the other type of twins two-thirds of all twin births are called D zygotic two zygotes they're they're like any brother and sister but they happen to be born at the same time in the same womb so the twin method consists of comparing these two groups if a trait say like musical ability is influenced by genetics you'd have to predict that the identical twins are more similar than the non-identical twins so it's like a biological experiment and what twin Studies have
• 02:30 - 03:00 shown us in a recent survey of 15 million twins that have been studied in um 4,000 papers everything is heritable not just in Psychology but in physiology skeleton Bon length density everything about individual differences in biology and behavior are substantially influenced by DNA inherited DNA differences is between
• 03:00 - 03:30 us so the twin method is one method the other method is the adoption method so the twin method is like a biological experiment you've got these two types of twins adoption is like a social experiment nature and nurture run in families so for a long time psychologists knew schizophrenia runs in families no problem that's the environment that's because the parents did weird things to them the parents made them schizophrenic but they ignored the possibility that genetics is important because genetics runs in
• 03:30 - 04:00 families parents and Offspring share are 50% similar genetically so the adoption method says let's look for genetic parents and environmental parents because kids adopted away at Birth those parents still gave them their genes but they don't see those parents they're their genetic parents but adopted children that are adopted into adopted families where the adopted parents are environmentally related so it's a straightforward powerful test of genetics because it predicts that these
• 04:00 - 04:30 biological birth parents who don't share environment with the kids how similar are they to the children is a direct test of genetic influence similarly how similar the kids are to their adoptive parents is a test of environmental influence so the twin and adoption studies um have convinced people that genetics is important so much so that um we've now challenged psychologists to come up with any trait
• 04:30 - 05:00 that is not heritable so we've gone from thinking nothing's heritable to realizing everything's heritable and what we're now doing is using these techniques to study more interesting issues for example about development how early does genetic influence appear and there have been some and the interplay between nature and nurture and I'll just give an example of that we have hundreds of measures of the environment that are used in social sciences
• 05:00 - 05:30 life events things like uh Financial disruption stressful life events are used in several thousand studies but it's just been assumed that environmental measures are environmental but what we've shown many people around the world these environmental measures show almost as much genetic influence as other psychological traits and when you start thinking genetically you say that's
• 05:30 - 06:00 that's not crazy what are these measures it's not the measure of the environment out there which is the way psychologists used to think of it the environment is what happens to us what's going on is that in Psychology our environmental measures are measures of our experience so life events it's like Financial disruptions having trouble with relationships getting in fights with people losing your job this is not the environment out there that happens to you passively you don't have anything to do with it it's what you do
• 06:00 - 06:30 with your environment and that's where the genetics comes into it so that's a good example of how a genetic perspective has changed the way we think about the environment and I believe it's a fundamental principle that the way genes work is through their correlation with the environment how we use our environment for example I study cognitive abilities the most heritable measure out of the hundreds of measures of cognitive ability is vocabulary and so people say so I'm talking about
• 06:30 - 07:00 individual differences some people have big vocabulary some people don't and um you don't inherit the words it's not in your DNA because of different languages for example what it is is a propensity to use language to be cognitively aware of the subtleties I have one grandchild who always wants to know she's about seven the nuances well does that word really mean this or does it mean that I've got another grandchild who says whatever you know you know what I mean what does it matter you know and
• 07:00 - 07:30 and you know that's how genes begin to work is you begin to use your environment you hang out with people who are likeminded you know the one will the one grandchild will be hanging out with other kids who read books who are interested in intellectual conversations language development has been studied a lot um children differ greatly in their how early they learned to speak um Einstein didn't begin to speak till he's about three and also how they develop
• 07:30 - 08:00 throughout life in terms of verbal fluency how easy they find it to talk fluently and also vocabulary so that's your first language learning so an interesting question that behavioral geneticists have begun to address is about learning a second language how does that fit with it and it turns out that many of the same genes are involved so people who are good at verbal measures in their first language will tend to be pretty good in a second language but there are some specific genetic
• 08:00 - 08:30 factors so the bottom line of that research is that about a a third of the genetic influences on learning a second language are overlap with uh the ability to learn a first language but about a third of the genetic effects are uh different and then about a third overlap with just general intelligence these swin and adoption Studies have been used for most areas of psychology that
• 08:30 - 09:00 involve individual differences that is we're only asking about what makes people different 99% of all our DNA is the same we're all identical but we're asking the extent to which the 1% of DNA that differs makes people different that's what we're doing in behavioral genetics we're studying differences so much of psychology and the life sciences is not asking about individual differences they're just asking about Universal questions about the human species but we're asking about why are some kids reading disabled others not
• 09:00 - 09:30 why are some schizophrenic and others not a real transformation of research in this area up until now people have been concerned about just simply asking whether genetics is important and then asking how important that question's been pretty much answered across the board there's some people still don't accept it but the vast majority of people do not only is genetics significant it's very substantial for almost every area of psychology that's been so so well- ingrained that it's no longer
• 09:30 - 10:00 interesting to say this tradeit is heritable because everything's heritable we go beyond that to ask questions about development about the relationship between traits like a big issue right now is in in Psychopathology and mental illness there's all these different diagnoses it turns out the genetic effects are pretty much the same that is the same genes are causing many of these so-called different disorders so that's an example of a multivariate approach and a third area First Development
• 10:00 - 10:30 second multivariant the third area is the interplay between genes and environment if both nature and nurture are important as they are because genetics doesn't account for all the differences it's usually accounting for about half the differences so if nature and nurture are important a lot of researchers interested in how they work together the interplay the correlation and the interaction between genes and environment as they affect development but the biggest thing of all is to go beyond heritability to say let's find
• 10:30 - 11:00 the genes so that's sort of molecular genetics and that's the hot thing now things are heritable fine let's find the genes because if you can find the genes you can do so much more in terms of research but especially in terms of translation to important problems DNA is the best tool we have for predicting problems which allows us to intervene to prevent problems which is the way all of
• 11:00 - 11:30 medicine is going you know rather than waiting until you're alcoholic and then try to cure that until you're obese and try to cure that if you can predict who's going to have those problems you could intervene to prevent the problems which is much more coste effective for the individual but also for society so the excitement now is about trying to find these genes and we're at the turning point where we are beginning to find genes which will allow us to make individual predictions about genetic
• 11:30 - 12:00 risk and resilience you know vulnerability and strength which will eventually allow us to predict problems and then hopefully begin to prevent them