If anything is going to put him off being a girl, it will be those ankle breakers, all that time it takes to put make-up on, and the way sometimes womens clothes are restricting in what you can do, i.e. doing cartwheels and climbing trees in skirts! I'll give him two or three months of that stuff and if he is not totally shrugging it off, THEN I would start to look into the reasoning. Even then, I would not worry! ;)