I've run into this attitude quite a bit. Worked in 4 person section. Two obvious white guys, one guy who looked like a tanned white guy but had a Slavic last name, and one obvious Sikh. Three of us never got asked where we were from, one did. Guess who. The ironic thing is the Sikh was born in Mississauga. The other three of us were born overseas. Was funny at first but got old pretty quick.
In today's society, anyone who is in still asking about origin and doesn't understand that people can be from anywhere harbours rascism somewhere in themselves.
Age doesn't excuse ignorant behaviour. It should be corrected on the spot and it the correction doesn't take more measures should be taken. As is the case here.
I've taken to asking if someone was born in the town I'm in, or if they moved here from somewhere else in the province. That allows them to answer how they want.