I got an explanation once and it made even less sense. The woman said some shit about how race carries with it the collective history of the people of that race. If you're not black, you can't become black because you didn't experience blackness as a culture growing up. Bitch then went on about slavery and oppression and how someone of privilege can't understand what it is to be black. I asked if this meant women were never oppressed, and so a man CAN become a woman because of their privilege. She said I was being purposefully obtuse.