To answer this we have to ask: What is a man and what is a woman? Every culture seems to have their own norms of what that means and in some cultures there are no binary genders at all. In the US, it is the norm that a woman can dress in typical men's clothing (pants, or even suits) without being scrutinized, but a man dressing in typical women's clothing (like a dress, or a sparkly top) is seen as a diversity.