When gay people are asking people to join their groups, they are asking other gay people or closet homos. But of course gay people try to convince attractive straight people to be gay.. just like I try to convince beautiful pixie lesbos to like my dick.

edit - And your biological argument means nothing if you are a guy and you get a boner when looking at another guy, and beautiful girls can take their clothes off and drape themselves all over you and your could care less.