So of course, I'm used to being asked about my ethnic background a lot, and for me, it all depends on who's asking, why they want to know, and how they approach the question.
Two young co-workers asked me about my ethnicity today--it's funny because one was afraid to ask and coaxed his co-worker to inquire instead. The one who really wanted to know is Native American; the one who actually asked me is of mixed (black/white) origin. The first guessed I was Chinese; I gently corrected him by stating that I am Korean.
Which always leads to the million-dollar question: "Are you from the North or the South?" Or, as my poor sister-in-law gets asked, "Are you a good Korean or a bad Korean?"
Seriously. I think I should get at least $100 every time I have to answer this question. I understand, I really do, but... Sigh.
And I always give them the same answer: "Seeing as anyone from the North would get shot on site for trying to leave... I think you can kind of guess which one I'm from."