A friend of mine asked me a while ago what I thought about homosexuality in light of evolution. I thought about it for a while and googled it a bit, but I'm not sure I've found a satisfactory answer.
I currently believe that humans (and every other animal on the planet) are basically bags of animated DNA whose ultimate goal is to survive long enough to procreate in order to continue the particular DNA that each is created from. This is largely unconscious, but we all fight for survival. Supposing this is true, one would think that homosexuality would not survive hundreds of thousands of years (assuming it has been around that long) due to the natural evolutionary process. But homosexuality is alive and well in the human species. Why do you think that is?
Richard Dawkins has some ideas on this that can be seen in this video. Other studies show that female siblings of male homosexuals are (or can be) more fertile than females from other families with no instances of homosexuality. Perhaps sexuality is not this or that, but more like bisexuality. Homosexuals may go back and forth over their lifetime. Perhaps the number of homosexuals are not large enough a number to really affect the number of homosexuals that occur at a later time in the population. Or does this point to either no genetic component for one being homosexual or not, or that social factors also play a large part.
My friend had an interesting thought in that, except for small areas and certain times, homosexuality has in general been frowned upon by society. In order to fit into society, homosexuals (male or female) would adapt their behavior by playing the part of a heterosexual by getting married to a person of the opposite sex and having children. These people would either suppress their nature, express their nature in secret, or perhaps 'come out' later in life after they had already birthed and raised children. He postulated that, accepting and allowing homosexuals to be who they are would prevent these people from playing such roles resulting in less homosexuals procreating. (wouldn't that just blow some people's small minds?). It's an interesting theory. I have know idea if it has any merit though.
I wonder how others see this issue.