Hello and welcome to PC!

I would think that you are now having these concerns about transgenders because it has been a big issue in the media lately. You might be thinking 'what if they look exactly like females and I can't tell the difference?'

Chances are, the females are females, and you can usually tell when to question. If you feel like you need to question someone about being female, do it very gently. You can be honest and say you have this awkward fear and that they shouldn't take it personally.

If they are transgender, I'm sure they'll tell you.