This isn't stupid; I often want to say "I think what he ment was..." and then I have to stop myself because I don't know the gender, and if it's a girl she may be offended, and vice versa.
A lot of people think I'm male (online AND offline), but I'm a girl. I'm quite masculine looking anyway, so it doesn't really bother me. I voted Not Telling, because I see myself as androgenous.