Thursday, March 25, 2010

Genetics and Orientation

Is it a choice, or is it hard-wired? Apparently it does make a difference to some people. Support for GLBT rights increases when people recognize that it's not a choice, leading to the loaded argument between terms like "sexual preference" and "sexual orientation". One post I read commented wryly, "my preference is to be tall; alas, my orientation is distinctly short." Like height, sexuality is a complex trait, which is not going to be completely determined by a single gene, or even several genes, but rather the interaction of multiple genes and the environment. Indeed, no geneticist buys a genetic determinism argument for complex traits. But since it keeps coming up, it might be worth a primer in genetics to explain why. In an extended series over the next couple of weeks, I will explain some basic genetics, and then address some of the issues that come up when we apply genetics to understanding sexual orientation.

As stated in this excellent LA Times op/ed,
Moreover, the empirical evidence for the role of genetics in human sexual orientation has been quietly but steadily mounting over the last 15 years. Studies of twins -- the mainstay of quantitative human genetics -- have been conducted on large populations in three countries. The results unambiguously demonstrate that heritability plays a major role in sexual orientation and far outweighs shared environmental factors such as education or parenting.

I'm focusing here on genetics, which is my field. For other general audience discussions of the science of orientation, there's a good article in NY magazine: The science of gaydar.

As I post my Genetics series, I will add the posts to a static page (see that tab for "Genetics Page" at the top of the blog) so that the whole series will be accessible in order.

There will be no examinations, and you don't have to pay tuition. What a bargain!

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