Well, mixed race people can ID as any, all or none of their ethnic heritage. I think most people who get into trouble for not being black, or Asian or white “enough” are actually mixed race.
In addition, there are trans-race people. These are people of one race adopted and raised by people of another race, that then go on as adults to claim their ethnic heritage. It sounds easy, but it’s actually very hard. Because most often you’re raised in an entirely different culture. Think Chinese orphan raised by US white parents in Ohio. You grow up with different language, different concepts of family, of traditions, of religion.
Now as for the people clearly of race X, not mixed race and not raised by another race, but decide to claim they are race Y....its not the same as being a man wanting to live as a woman. Biologically, you cannot change your sex as you cannot change your race. But socially, you can change your gender to live as a woman.
I see nothing wrong with that and the more the line is blurred between man-woman gender construct, the more we get rid of gender itself, I see that as ultimately freeing and leading to equality between the sexes. I don’t care as much about who gets to claim actual victimhood for oppression of women. It’s about the future not the past.
It’s kind of a sad truth, but take for example historic women’s work....usually unpaid, when paid mostly women workers and of course underpaid. But when men start doing that work or those jobs, it suddenly gets better paid and more equal to jobs historically done by men to begin with. Take childbirth- once the exclusive preserve of women, now we have highly paid OB/GYNs...both men and women doctors. As opposed to an older woman of the village who popped by and assisted with childbirth in exchange for a chicken or whatever.
I think the same is happening here with men choosing to live as women and some women choosing to live as men. At the very least if they go through the surgery and then pass in society as opposite gender, they are getting a taste of what it is like to live without (or with) male privilege. In fact, it’s a shock to most transwomen and in my opinion, 99% of their discrimination claims are due to discrimination the experience not because they are trans, but because they’re being treated as if they were a born woman. And if you’ve lived as a boy/man and then start passing as a girl/woman, it can be a shock to lose that male privilege in society.