Unfortunately, the conversation is not really about ancestry at all, is it? We are not specifying that "a significant portion of your ancestors were from x or y region somewhat recently". We are saying "you have physical features that we identify with persons of x or y region, but which may or may not be accurate per your own ancestral history". So why obfuscate the conversation by mentioning ancestral locale in the first place. You are talking about people of x or y skin colour and facial features. Furthermore, you are talking about these people whether or not they are, in fact, "American". Personally, I suggest we come up with some terms that describe the features we are attempting to explain. Let's say Browns, Tans, Yellows, Pales, and Reds. Perhaps not entirely accurate, but at least we would then be consistent with the concepts we are mentioning. And, yes, these are offensive and horrid to say, but then perhaps enough people would be done mentioning race to begin with and we would be able to stop classifying ourselves under such arbitrary and ridiculous measures. We could get down to what's really important... pro-Skub or anti-Skub.
Re: proper terms