My son is wearing my clothes all the time and he is like the daughter I never had and he told me he wants to become a girl should I let him?

There is a great deal of debate currently on this issue. On the one hand, your child may not be transsexual or transgender, and in that case this may only be a phase. On the other, your child may be transsexual or transgender, in which case you will have to figure out a way to deal with this in the long term. There are many trans individuals who have horrific childhood stories about how their parents attempted to enforce gender norms. In the end, the punishments solved nothing and left them broken individuals. While you may not agree about whether transgender behavior should be allowed, keep in mind that such things can scar a child for life. I would recommend an open-minded therapist with a penchant for actually tuning into a child. Not one who will either insist on rigid enforcement of masculinity, and not one who is likely to say that any child who plays around with gender roles as a child is transgender. There are some interesting new documentaries about transgender children and parents who let them be who they are. Before making a decision, I suggest maybe watching some of these, and looking at both sides of the debate. Another thing I would suggest is, at least for a little while, to let your child wear what he wants to around the house, and to play as he likes. Don't try to encourage him or discourage him in this. See how it works out. He may just like the forbidden nature of this, or he may grow out of it.