But the
logic of mblase's writeup presumes that there is no
benefit in being
homosexual, either for the
individual or the
species. While the
biological advantage of
heterosexual intercourse is that you can produce
children, perhaps the advantage of
sex with someone your own
gender is that you
can't. The 'tribe' needs
maiden aunts to care for the
children, and
population growth can only go so far. Maybe the
contribution made by the
childless is so great that a
population can't live without it.
So, back to the heterosexuals. Who knows what causes it? Certainly on an individual level, for women heterosexual intercourse and resulting childbirth has been the greatest threat to their survival. One for one, there's no advantage in reproduction for women.
It's going to wrench your mind into 23 pieces whichever way you look at it. Perhaps the reason we don't usually debate the reasons for people being heterosexual is simply that they're the majority. And most people are normal, right?