It turns out that gays are different from heteros in a number of minor ways....finger length, hair whorl direction, handedness....not that it all adds up to anything decisive, but it is interesting all the stuff that people are studying in relation to gayness. I wish there were some broad endocrinological studies, of the mothers during pregnancy, of the developing children, and of the sexually identified adults. I think hormones are the main reason why some people are gay, though of course there can be many factors.

Here's an interesting article, by a gay man, about the difference:
http://nymag.com/news/features/33520/