I think a lot of ppl, gay & straight, agree with you. I already mentioned the current genetic explanation. But my understanding is its generally more an opportunistic behaviour than a preference (i.e. those who would consistently choose a same-sex partner, given that choice, only seems to be around 10% of the population).
What are you going to do when you feel the urge for children, DL? Or haven't you had that urge yet? All the men I know get it somewhere b/t 25 - 35 years of age.