to ans the question of why some ppl are gay..well, let me ask
you, why are ppl straight? why do some ppl like apples while some
likes oranges? Its a matter of preference...
gay ppl of course go gay places, gay pubs, discos, clubs etc
etc.
- not all gays want to be girls.
- some gays are even more manly then so called straight
guys...
- as for gay ppl being more sexually active...i cant say..but i
think the fact that its easier to come in contact with another same
sex person has something to do with it...
- most gay guys are more sensitive then straight ones 
- as for bad tempered, bad altitude? remember there are lots
straight ones who are same or worst..or maybe her bro could be
trying to accept himself or trying to come to terms with himself
and thus going thru some stuggles..
- lots of so called straight/MARRIED man still has an active gay
life...
ask your friend not to encourage but at the same time dont condemn
for what her bro is...remember most gays did not *choose* to be
gay...i think her bro needs much support if he is at a stage where
he is trying to come to terms with what he is....