it's mostly natural, inborn, though i'm sure some people try to accentuate it.
remember those "sissies" from elementary school? fags. 75% of gays give themselves away with the way they pronounce their S's...i wouldn't call it a lisp, per se, but it's VERY easy to pick out, even from across the room.
personally, any time i notice ANYTHING which even remotely seems to make me seem "gay" i try to eliminate it. maybe that's wrong, but i hate to be at all stereotypical.
johnny, PM me your voice mail number. now i'm curious.
johnny and i both live in houston, both gay, both dashingly handsome (okay, maybe THAT'S a slight overstatement), yet we've never met.