There are many women who have 'masculine' interests and men who have 'feminine' interests. That doesn't mean they are transgender. Gender identity isn't the same as gender expression. I could be out in the middle of nowhere with no one around me and still feel like a guy, even though there is no social element. So, while gender expression has it's social element, gender identity does not. That's also why changing gender expression can't change someone's gender identity - in fact gender identity cannot be changed as far as is known today.