How Do Genes Influence Our Behaviour? - Robert Plomin | Modern Wisdom Podcast 353

Well, for IQ, siblings correlate about 0.3 in childhood, about 0.4 later on. How much do these adoptive sibs correlate? Because they grow up in the same family, they have the same parents. Zero. So the fact of growing up in the same family isn't making them similar. (wind blows)

You turned my world upside down last year-

(laughs)

... when I read Blueprint. I, uh, I've been wa- looking forward to speaking to you ever since I read that book, and I'm hoping that today I'm going to be able to deliver the same uncomfortable, topsy-turvy world that I was, I, I sort of slowly ingested about 12 months ago. So I'm looking forward to seeing what the audience make of the insights that we're gonna get from today.

Yeah. Well, that's, that's terrific that you got it, you know? I, I, some people I think just get turned off. They just say, "Whoa, this is too weird." But, um, it, it really is so rewarding for me when people, you know, persist with it, they're willing to deal with these difficult topics. And then when you get off on the other side, it isn't so bad. It's actually exciting. It's a new way of seeing the world, I think.

I thi-

So that's terrific. I'm really glad to hear it, Chris.

... totally correct, like it is a whole new world. And you, you're also right to say that today there'll be some uncomfortable insights, especially when we're in a meritocracy, you know, a meritocratic society that's capitalist and you are your achievements, to hear that there are these immutable truths that you perhaps didn't choose, there are influences on you that you didn't elect. These things are uncomfortable. But I, you're also correct that it's very liberating if you take it just a little bit further, it's so liberating to learn. So, okay, we've danced around it. How would you describe behavioral genetics to someone who's never heard it before?

Well, behavioral genetics is like medical genetics in it's not the genetics of medicine, it's the genetics of behavior. And behavior is essentially psychology. So we're dealing with the major domains of psychology, like psychopathology, personality, cognitive abilities, even getting into education, educational achievement. But the main thing is we're focused on individual differences. Why are some people schizophrenic and others not? Why are some children reading-disabled and others not? And it's an important distinction, because, um, genes, uh, um, we're 99 point say 9% similar for all our DNA. Three billion base pairs of DNA, we have exactly the same DNA at ... These are the steps in the spiral staircase of the double helix of DNA. We're, we're identical for well over 99% of those bases. But for at least 0.1% or so, which still means millions of these steps in the spiral staircase, we differ. And so what we're asking in behavioral genetics is the extent to which those differences in inherited DNA sequences make a difference in our behavior. Do they make us more likely to be susceptible to schizophrenia or depression or alcoholism, or do they affect our personality? So it just can't be emphasized enough that we're talking about individual differences. The other 99.9% of the DNA is the same for all of us. That's what makes us human. And those are also important questions. You know? Is that, that, is that why, for example, humans are natural language users, or we walk on two feet, which is very rare. We have eyes in the front of our head for depth perception. So those are questions about universals. Why is the human species like this or like that? Those are terrific questions, but we're not looking at that. We're asking about why people differ and the extent to which inherited DNA differences make them different.