We want to encourage more female gamers to the scene and/or find our how many reside here so the question is aimed at females. Transvestites are still the sex that they are before they dress up. I mean if you are a serious transvestite then maybe you think of yourself as female anyway so that will be the option they can vote for. Some people may also not want to vote to say they are a transvestite.
This is all part of a bigger plan that the girl admins are having