That well meaning curiosity is the America I know.
I was born in North Carolina, I speak with a textbook Piedmont white guy drawl. I'm as American as high fructose corn syrup, no question. Here's some hell I've caught: Europeans struggle to cope when I describe myself as "German and a little Scottish." To me, that's my ethnic background, to a lot of Europeans I've argued with, it's stolen valor. "You're not personally from Germany, you aren't German." Then explain my genome. Or my surname.
I think us who live in the New World have a whole different understanding of diaspora.