UM Professor David Lykken has spent his career studying the role of nature and nurture in shaping people. And he believes his research shows the best society would be one in which the state decides who gets to have children.
by Jennifer Vogel

           But everybody accepted it in those days. The pendulum has swung back the other way. I think the biggest single obstacle to genetic research was Adolf Hitler. There are a lot of people now, even psychologists and geneticists, who think that if you believe that the genes have anything to do with the mind, you must be a secret fascist.

           CP: How do you respond to people who say that about you?

           Lykken: I've stopped arguing with them because these people are getting old, as I am. And I think that they'll never be convinced and we'll just have to wait for them to die off. I am encouraged by the fact that people, journalists in particular, and I don't know how many journalists I've talked to about these different things, seem to find this perfectly reasonable. And the studies are accumulating and the resistance among the better academics has fallen to a whisper. And so now, we know there are a half-dozen names that still resist this sort of thing, names of otherwise respected scientists. But it's a group that doesn't seem to be growing.

           CP: If most twins are reared together, how do you sort out which traits are genetic versus environmental?

           Lykken: Because identical twins share all their genes. Fraternal twins, like ordinary siblings, share, on the average, about 50 percent of their genes. And so, if genetic factors are playing a role, the identical twins should be more similar than the fraternal twins. And by appropriate statistical manipulations, you can actually make an estimate of the heritability. Also, of twins reared apart we have been able to show that for almost every trait that we have measured, and we are talking now about dozens and dozens of psychological traits, the similarity of identical twins reared apart is as high as the similarity of identical twins reared together. And what that means is being reared together in the same home does not tend to make you more alike as adults. That is true for the broad middle range of society, that is for middle-class people.

           It is not true, I think, although this has never been studied, for the underclass of society and I think that common sense would suggest that if you take two foster children and give them to a single mother on welfare to rear who is overburdened or may be unsocialized herself or uneducated, she isn't going to do as good a job with those kids as a better educated, more mature mother would do.

           CP: Do you see a genetic difference between people in the middle class and people in the underclass then? Or are any differences environmental?

           Lykken: Nothing is entirely one way or another. We do know that because our society has become a lot less arbitrary and stratified than it used to be, and we have social mobility so people can rise and they can fall, there are differences in genetic characteristics. For example, all the excitement about The Bell Curve was based on the fact that people are made nervous to learn that people higher on the social ladder have higher IQs than people down here. People don't like to believe that.

           CP: But you consider that to be true?

           Lykken: Oh, yeah. There is no question about that. There is no question about the facts regarding the stratification of IQ. And there is no question that IQ is strongly determined genetically. And it all makes perfect sense. It would be very difficult to understand our not finding this stratification since there is social mobility and since people with higher IQs are likely to get better jobs and better education and to move up. And people with lower IQs are likely to move down. It's inevitable.

           CP: You don't think that factors like race or sex discrimination have anything to do with it?

           Lykken: Race is a different issue. There is a big IQ difference between blacks and whites in this country, there is no question about that. It's about a 15 point difference in the average.

           CP: And do you think that difference is genetic?

           Lykken: Just a minute. We know that among whites, the individual differences in IQ are about 75 percent determined by genetic factors. That has been clearly demonstrated. I mean that is standard mainline scientific opinion. We don't know that the heritability of IQ is as high as that among blacks. The reason is there haven't been enough studies, twins studies among blacks. If we did know that, if we knew that heritability was the same among blacks as among whites then it would be hard not to believe that the IQ difference between the two groups was genetically based, in part at least.

           But we don't know that. So it's impossible, and remember this, the heritability of a trait tells you as much about the culture as it does about human nature. The fact that the heritability of IQ is 75 percent, at least among whites, tells us that we have been able, for most of the white population, to provide equal opportunity. Reasonably equal opportunity. I mean if you go back to Dickens's time, and do the same study, or do a study of identical twins reared apart where one of the twins ends up being reared by an aristocrat and another one being reared in some gin mill in east London, then you would not have found the results on that study that we've got now, because the environmental variance was so much greater in those days than it is now. Now the environmental variability relevant to IQ among blacks seems to be a lot higher in this country, so it may be that the heritability among blacks is lower.

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