Anal travel

So I'd like to try anal intercourse but I am not a homosexual or anything etc..

I've been doing some research on the internets and wondering if I should take some courses at uni or something, will acting like a homosexual make me a homosexual?

if gayness is caused buy a gene then why hasn't it died out and been removed from the gene pool? after all im pretty sure buttsecksing other guys doesn't produce offspring. and why does gayness seem to cluster in certain areas(san francisco).