Sometime ago I wrote a post about how you can ask people's ethnicity without looking like a foolish git, here -> http://alexeastasian.blogspot.ca/2013/05/so-what-are-you.html
Interestingly enough, I just read an article on jezebel.com by a certain Meher Ahmad about the same topic, here -> http://jezebel.com/how-to-ask-someone-about-their-ethnicity-without-being-758679070
Seems we share more or less the same view on the matter, though she adds a point that asking about someone's ethnicity "without looking like an asshole" is also about timing, as in it shouldn't be the first thing you ask right after introducing yourself. Well, I couldn't agree more, and for basically the same reasons she states in the article (read it, it's short). She also states that asking where one's parents come from is inappropriate, and I also agree with this, because you're just making too many assumptions with that one. I feel it may be be similar to asking "Where does your family originate," which I offered in my post. But then again, the word originate, I feel, specifies ancient origins rather than referring to anyone presently living in the country where said person lives. For example, if someone asked me that question I couldn't say "Canada" because it simply wouldn't be true. For the record, my family originates partly from the British Isles and partially from Eastern Europe--Belarus and Czechoslovakia, to be exact (as far as we know). Regardless, one of the methods she suggests is not asking at all, because the person will likely at some point reveal their ethnicity if you talk to them long enough. I have found this to be quite true in many cases. Just remember it's okay to be curious, but to assume makes an ASS out of U and ME.