I've posted this a few times over the years and never gotten much feedback. (Disclosure: I am a straight, married guy with kids, but teh Gayz do not icky me out)
Was gonna hit up moonbeam and get his take on that.
One way to test it would be to examine homosexuality over disparate populations - e.g. in struggling third world nations where violence, disease, etc yields a short average lifespan, versus a much more stabile society with a long average lifespan.
Maybe I am way off the mark, but I have been thinking for about 10 years that it is much more prevalent in the latter, and that leads to pretty much only one conclusion...