Why would they choose again? They should be happy with who they are. No one else minds, and if they do, they're the ones who should be rethinking their attitudes.
As a gay, if you are given a chance to choose again what do you like a boy or a girl?
According to gay and lesbian people I know, it never was a choice.
As Tyto says, this question is fundamentally flawed (and in other circumstances might be considered a bit offensive).