Of course it's impossible to literally become homosexual. In your example there are people for instance who act black, but are not (think eminem). No one argues

Of course it's impossible to literally become homosexual. In your example there are people for instance who act black, but are not (think eminem). No one argues he has physically become black, but has adopted the many things that go with that. So please don't be under any illusion that when it comes to a topic as subjective as sexuality one must always be born homosexual or otherwise to claim to be one or the other.