You’re describing my definition of ignorance. When we (and all humans are guilty of it in some capacity) don’t understand each other, we immediately move to sort people. Yes. Sort people.
We judge each other like we would a pair of shoes or (like you said) a shade of nail polish, but here’s the thing:
Nobody wants to be treated like an inanimate object. We get offended, and those that offended us get uncomfortable when we’re offended.
Which doesn’t make them want to get to know us well enough to move past the dichotomous stereotypes we all use as crutches.
At our core, stuff like this is innocent. Humans have that innate need to explain things, but when exploring further puts us in uncomfortable situations, the majority of us fall back on the crutches.
What do you say to people who tell you you’re not black? I’d like to think that at least a few people (definitely not all people) would respond thoughtfully to a slightly more condensed version of what you wrote here.
If it’s a case of someone just being ignorant, then you’ve just helped them learn.
If it’s a case of someone being just plain mean, tell them they’re “too white,” and watch them wrestle with that one for a while.