More on biological v. genetic causes
Mark Kleiman highlights the "biological = innate" confusion when he writes about the pheromone study I commented on yesterday, "if the laboratory result holds up, the argument that the sexual orientations of males are hard-wired, rather than chosen, just got much stronger." In fact, "hard-wired" and "chosen" are perfectly compatible - any choice you make will naturally be reflected in the wiring (or some other biological aspect) of your brain. The mere fact that homosexuality has a neurobiological basis tells us very little about whether homosexuality is innate, learned, involuntary, or chosen.
Rather than looking to biological evidence for the innateness of homosexuality (which will be found not in the biology of adult brains, but in genes and possibly the biology of fetal and infant brains), we should look instead to the actual experiences of gay people - the vast majority of whom say that they didn't choose to be gay. Isn't that enough?