In answer to the original question, I'm not gay, but I am bi. I know it's not specifically what you were asking about, but I figure it's relevant, and assume you meant to ask about sexual minorities in general.
I may or may not wade in on some of the other topics being discussed here, I've certainly read and seen enough of every single topic being discussed here, that I don't necessarily feel the need to jump in, as usually someone else says what I'd say better, but we'll see. I have a tendency to get sucked into these things ;).
I will however just throw my two cents into the "nature vs nurture" bit that's shown up here toward the end. In my experience, in just about any situation in which there is a debate about whether something is caused by "nature or nurture" it's nearly always both. Maybe in different proportions, but usually it's both.
In this discussion, chances are, there are both genetic and social reasons why anyone ends up on whatever point on the spectrum of sexuality they end up at (not to say that some people don't move around in their sexual interests throughout their life. Again probably both genetic and social reasons).