No, you can't be born gay. That just doesn't make sense, the largest instinct in the human body is "make babies", which cannot be done by sticking your richard up someones ass, and the only thing powerful enough to override it is the mind. That's when you make the choice to be gay.
If we could have random loveual sides when we were born then snakees wouldn't be strictly for males. Being brought up gay is different story but you can still make a choice to be straight, like you can make a choice to be gay.
I have nothing against gays, as long as they don't rub it in my face then act like they can't do anything about it.