I'm not sure "I was BORN that way" is *always* intended as a 'you have to forgive my terrible terrible failing, I can't help it'... Arguing on the stance of what's "natural" only makes sense if you're fighting with someone else who's already tried to call that corner. If you've got religious nutcases yelling at you to behave 'as God intended', it's an obvious response to point out that God made you gay! :) Not a 'forgive me this sin' but 'this is perfectly normal, shut up'.

But then, what's "natural" is a silly argument to begin with, really.

if your defence of gay rights hinges on the idea that homosexuality is an inborn trait and not a voluntary choice, what do you have left when somebody offers you a medical 'cure' for the hereditary component of orientation?

At the risk of touching off an enormous flamewar, I will very quietly mention the deaf community here. Some people are very touchy about the idea of being 'cured'.