You may think it's wrong, but a professor at the University of Pennsylvania and the former president of the American Psychology Association would disagree with you. There is a chapter in his book (http://www.amazon.com/What-You-Change-Cant-Self-Improvement/...) where he talks about gender identification as nature or nurture.

He argues, quite convincingly, that girls raised as boys still like dolls and boys raised as girls still like firetrucks and bulldozers.

I would recommend the book.