Blank slate when you want it that way

Gene ExpressionBy Razib KhanJul 11, 2011 8:44 PM


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Tim Pawlenty debates Lady Gaga's 'Born This Way' idea:

Gregory pressed, asking "Is being gay a choice?" Pawlenty ultimately said, "I defer to the scientists in that regard." Again, Gregory pressed: "So you, you think it's not a choice. ... That you are, as Lady Gaga says, you're born that way." Said Pawlenty: "There's no scientific conclusion that it's genetic. We don't know that. So we don't know to what extent, you know, it's behavioral, and that's something that's been debated by scientists for a long time. But as I understand the science, there's no current conclusion that it's genetic."

This is one issue where the American Left has a tendency to be on the side of the hereditarians. In contrast, the American Right emphasizes the plasticity of human behavior, and its amenability to cultural pressures and individual will and contingency. Transpose the structure of the arguments to male-female sex differences, and many of the basic elements would be preserved, but those espousing them would invert politically. One issue which needs to be clarified is the distinction between something which is explainable by genetics, and something which is not explainable by genetics but may still have a biological basis. It does seem that homosexuality is only modestly heritable. That means that genetic variation can not explain all the population wide variation in sexual orientation. The correlation between identical twins on height is much tighter than when it comes to homosexuality. Does that mean then that since so much of the variation in homosexuality is "environmental" it is amenable to change? Let's focus on male homosexuals, as the heritability estimates for female homosexuals are so much lower. "Environment" in these heritability estimates means a lot of different things. It can include what we normally think of environment, socialization. But it can also include pre-natal and post-natal developmental randomness which induces unpredictable biological variability. Then there are the mysterious changes wrought by infection. Finally, even non-linear gene-gene interactions are often included in the "environmental" component. In other words, even if most of the variance in homosexual behavior can't be explained by variance in genes, that doesn't imply that a male who has a homosexual orientation at the age of 12 is going to be able to change that through behavioral therapy with any ease. At the end of the day I doubt we'll fine a "gay gene" in the near future. And without that, people like Tim Pawlenty will continue to take the stand they're taking now. Revised upward heritability estimates wouldn't change anything either, if people don't want to believe that a behavior has a strong biological basis for ideological reasons, unless you can offer up a robust concrete genetic association they'll keep denying in my experience. But a bigger meta issue has to be "so what?" If homosexuality has a biological basis, then in the long term one can imagine that someone could devise a "cure" for it, just as they have claimed with today with talk therapy and what not. But that's the long term. In the short run it does seem that if something is biological the naturalistic fallacy will loom large in our political debates.

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