exactly! you worded it better than me. race is entirely dependent on what the mainstream culture sees you as. what they perceive you as. yet, every culture across the world knows what a man and a women is. there might be differences in terms of gender stereotypes but those categories exist in every culture. while race, like you said, is trickery and thus should be much more permissible vs immutable things like sex. yet, despite race being much more interpretable than sex, transracialism is a no-go.