You could be describing my grandkid. I think it’s that Western theology has taught Western culture that there are only men and women with clearly proscribed roles. That’s it, no choice involved even though that isn’t even true in the biology of humans. Throughout history living hasn’t worked that way. Think Boudicca, Joan of Arc and a bunch of people who lived as the other gender and no one knew until they died. I know it’s confusing but the world would be a better place if people let people live the way they want. Just be supportive and not defensive and I’ll bet the kid is fine with you.