Kieran Healy's Weblog has a post on plling data that shows that Republicans predominately think that homosexuality is "caused by upbringing," while Democrats feel that homosexuality is caused by genes. He then provides this:

This confirms a throwaway comment I read a few years ago, I think in the context of the Bell Curve debate. Conservatives think that everything but being gay is determined by the genes and Liberals think everything except being gay is caused by the environment. There’s a moral there somewhere.

I think the formulation is off the mark about Conservatives. I don't, for example, think that outside of some cliche of snobby country club elitism, Conservatives would argue that criminal activity or business success are caused by genetics. There is too much Pelagianism in the Conservative warp and woof for that. I will, though concede that it seems that arguments about the genetic basis of IQ have a conservative bent, although this may be modern well-poisoning. For example, Justice Homes - a darling of the liberals in other areas - was a major proponent of eugenics. See Buck v. Bell ["three generations of imbeciles are enough."]

On the other hand, the snide remark about Liberals seems true. No liberal would be caught dead arguing for genetic differences in any form of behavior, such as criminality or academic performance, nonchalantly accept the most egregious assertions of genetic determinism if it involves the infinitely nuanced behavior known as sex.