I am a (male) ballet dancer, and I also happen to enjoy wearing tights and skirts as well. I've tried many "girly" things; some I liked, some I didn't.
I actually "dress up" less when I'm involved in a ballet production. Why? Some thoughts: 1. In the studio, the focus is on technique and form, not so much on what one is wearing. The training is in some ways a very technical, geeky, almost asexual experience. 2. Although people can and do cross-dress convincingly on the street, it is impossible for adults to do so in the ballet studio. Men and women have such different body shapes, and one's body is so exposed. For this reason, I think that ballet brings out increasing gender identification among both men and women. 3. Men are so highly valued in ballet; aspiring to be just like the girls seems to be pointless. 4. Ballet is a very conservative dance form. The last thing I would want is to be considered a "sissy" among the other dancers. The women seem to want very macho men to dance with. 5. During rehearsals and shows, I have to be "out there" so much, and I have to change clothing so much and deal with so much sweaty clothing, that I just want to pull on something comfy (sweatpants) and curl up in bed.
For these reasons, I think that ballet for me ultimately enhances my male sexuality. What I really like about wearing tights and leotard is being out there so exposed, showing off my body, in an environment (the studio) in which I feel safe. I also find it hard to correct subtle placement issues while wearing a T-shirt. Those are gender-neutral issues. However, we have gender stereotype in American that does not allow men to dress in exposed or flamboyant fashions. Maybe part of your son's desires stem from a desire to be exposed in that way, and "girly" ballet clothing is the only outlet for him.
Your son will probably always like to wear girly clothing. As far as ballet goes, however, it's a very manly thing to do. Part of his initial reluctance to dance might have been based on his realization of this fact.
-- Bob[/i]