Twins: And What They Tell Us About Who We Are by Lawrence Wright Page A
Authors: Lawrence Wright
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notes of the conversation, but when asked to produce them, he found that there was no reference to the twins' meeting or the mothers' having known each other. "I don't know whether I was told or I deduced it," he says now. Jim Springer says such meetings never occurred.
"God could appear to me in a dream and tell me the outcome of a perfect twin study, and my question to God would be, 'Okay, now that I know that the heritability is 0.469327, what do I do with it? Tell me what that tells me,'" says Lewontin, one of Kamin's coauthors. He criticizes the statistical practice of correlation, which implies causal relationships between genes and behavior that may have nothing in common. "If I look at people who knit and people who don't knit, I will make the following discovery: that almost everybody who knits has two X chromosomes and people who don't knit have one X and one Y. Now, how can it be that having two X chromosomes makes you knit? Well, we know the answer to that. Having two X chromosomes makes you into a woman. In our society it is culturalpurely culturalthat women knit. If we had looked at exactly the same problem in eighteenth-century England, we would have found that all knitters have one X chromosome and one Y, because it was men who did knittingit was an economically important occupation. We wouldn't want to say there are genes for knitting on the X chromosome, but we understand that there are genes that make you into a female, which in the present historical circumstance has as a consequence that it's okay for you to knit."
It is certainly true that statistics can be used to associate unrelated matters. Daniel Patrick Moynihan, a
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United States senator who is also a distinguished sociologist, rather famously made the case on the subject of IQ, when Southern intellectuals were asserting white-race superiority. Moynihan found a high correlation between intelligence and proximity to the Canadian border. The further south one traveled, he demonstrated, the lower the IQ. As is the case with race, however, the variation within a region is so great that geography is virtually worthless as a predictor of individual IQ.
The statistical detective work that behavioral geneticists have done has already prompted an extraordinary reevaluation of the architecture of the human personality. And yet Lewontin has claimed that "nothing we can know about the genetics of human behavior can have any implications for human society," a statement that is perhaps best described as wishful thinking on his part. Lewontin and his coauthors Kamin and Rose are socialists who believe that the rise of biological determinism has led to the political ascendancy of the New Right. They are no doubt correct. Society will organize itself around its beliefs of how human nature operates in the world. "The consequences of determinism reach out beyond theory," Steven Rose wrote, perhaps despairingly, in Nature in 1995. "If the homeless or depressed are so because of a flaw in their biology, their condition cannot be the fault of society, albeit a humane society will attempt, pharmacologically or otherwise, to alleviate their distress. This 'victim blaming' generates in its turn a sort of fatalism among those it stigmatizes.''
As the views of the environmentalists lose favor, the politics that have been built upon their assumptions crumble. There has simply been nothing on the environmental side to counter the power of twin and adoption studies. "When I point to the weaknesses of behavioral genetics studies, I'm not saying there are a
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whole set of marvelous environmental studies," Kamin concedes. "We don't know what in the environment affects IQ. There's just not a good study on the family environment."
So far, the molecular evidence that would buttress the statistical studies of behavioral genetics has been slow in coming. As scientists map the human genome, they have been able to identify a few disorders that are caused by a single
"God could appear to me in a dream and tell me the outcome of a perfect twin study, and my question to God would be, 'Okay, now that I know that the heritability is 0.469327, what do I do with it? Tell me what that tells me,'" says Lewontin, one of Kamin's coauthors. He criticizes the statistical practice of correlation, which implies causal relationships between genes and behavior that may have nothing in common. "If I look at people who knit and people who don't knit, I will make the following discovery: that almost everybody who knits has two X chromosomes and people who don't knit have one X and one Y. Now, how can it be that having two X chromosomes makes you knit? Well, we know the answer to that. Having two X chromosomes makes you into a woman. In our society it is culturalpurely culturalthat women knit. If we had looked at exactly the same problem in eighteenth-century England, we would have found that all knitters have one X chromosome and one Y, because it was men who did knittingit was an economically important occupation. We wouldn't want to say there are genes for knitting on the X chromosome, but we understand that there are genes that make you into a female, which in the present historical circumstance has as a consequence that it's okay for you to knit."
It is certainly true that statistics can be used to associate unrelated matters. Daniel Patrick Moynihan, a
Page 78
United States senator who is also a distinguished sociologist, rather famously made the case on the subject of IQ, when Southern intellectuals were asserting white-race superiority. Moynihan found a high correlation between intelligence and proximity to the Canadian border. The further south one traveled, he demonstrated, the lower the IQ. As is the case with race, however, the variation within a region is so great that geography is virtually worthless as a predictor of individual IQ.
The statistical detective work that behavioral geneticists have done has already prompted an extraordinary reevaluation of the architecture of the human personality. And yet Lewontin has claimed that "nothing we can know about the genetics of human behavior can have any implications for human society," a statement that is perhaps best described as wishful thinking on his part. Lewontin and his coauthors Kamin and Rose are socialists who believe that the rise of biological determinism has led to the political ascendancy of the New Right. They are no doubt correct. Society will organize itself around its beliefs of how human nature operates in the world. "The consequences of determinism reach out beyond theory," Steven Rose wrote, perhaps despairingly, in Nature in 1995. "If the homeless or depressed are so because of a flaw in their biology, their condition cannot be the fault of society, albeit a humane society will attempt, pharmacologically or otherwise, to alleviate their distress. This 'victim blaming' generates in its turn a sort of fatalism among those it stigmatizes.''
As the views of the environmentalists lose favor, the politics that have been built upon their assumptions crumble. There has simply been nothing on the environmental side to counter the power of twin and adoption studies. "When I point to the weaknesses of behavioral genetics studies, I'm not saying there are a
Page 79
whole set of marvelous environmental studies," Kamin concedes. "We don't know what in the environment affects IQ. There's just not a good study on the family environment."
So far, the molecular evidence that would buttress the statistical studies of behavioral genetics has been slow in coming. As scientists map the human genome, they have been able to identify a few disorders that are caused by a single
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