But you just said "people who share my ethnicity", which has nothing to do with race. People of any race can share your ethnicity. Is a black Mexican closer in culture to a Nigerian or to a Mexican?
I'm not sure you understand how governments work. That's ok. On a census, there's no box to check off every strain that makes up my ethnicity. There's a box that says "Hispanic". I'm being descriptive, not prescriptive.
You're right. My comment was uncharitable and US-centric. Sorry. I found it hard to not react because of the personal stake I feel I have in this sort of conversation. I'll try to do better.