your priest should check out
this article regarding why there are more gay people in some areas.
like others, i think it depends on a huge number of factors and the answer wont be the same for everyone.
i sympathise with cynthia nixon, i could have made a similar blunder to her though in my case it would be 'heterosexuality is a choice.' i've discussed this with a lot of gay men, or more specifically how they discovered they were gay, and for them it really was a discovery. my old housemate cracked me up, realised he was gay after catching himself wondering if there would be any other gay men at a party.
gender doesn't really factor into my assessment of someones sexual attractiveness, i'm one of these sexuality is a social construct bores, though don't know enough about the ideas to really bore anyone with them. i also find it odd that people talk about it so much. obviously there are important discussions to be had to ensure people are treated equally/respectfully, but beyond that i'm just not bothered about what other people do in their private lives.
here's some on topic listening.