They is quite a bit of evidence to suggest your sexuality, if not determined, is heavily influenced by the hormones you receive whilst in the womb and the affects this has on brain development. You may be able to control the way your fetal-brain develops, but the rest of the world clearly lacked your telekinetic powers
Homosexuals, even very manly ones (and what is manlier than two muscle-bound naked guys?) also tend to perform better at tasks otherwise dubbed feminine. Ironically women and gay men tend to be, this is what studies have shown, worse at reading a map in order to get from point A to point B (and on weekends point C) than lesbians and straight men.
Combine this with the lasting influence early infant attachments have on a person...you have to wonder how much control people really have.
If sexuality is a choice, then it doesn't exist, because people must choose who they are attracted to on a conscious level, which anyone whose ever looked at a person ever knows we don't do, you don't see someone and decide they are attractive as much as see someone and the 'unconscious' part of your brain makes the decision for you based on partially-instinctive factors. Males who say other males are attractive but are straight are doing so consciously. If we decide, males would also choose when to get boners, and hell no can we do that (which is a shame, because dammit why do guys always get one at the end of tests?)...
Besides, why wouldn't a person want to be gay? Guys are so much easier than girls, they can't fake orgasm for one (except through a complex process involving a hose pipe), and they also tend to be easier to figure out
I identify as straight but at the moment...I see relationships as pointless because I know I'd be useless in them, so might as well be asexual. Also if the right person were to come along I don't feel like it would matter if they were male or female...but yeah, t'ill I start making out with guys I'm gonna still say I'm straight.