When I saw this Guardian article I was delighted. www.guardian.co.uk/commentisfree/2010/mar/03/racist-question-brown-answer-curious
It wasn't just me! In fact Ariane was much kinder than me, for stating she didn't believe it was racist. But the 1400+ comment debate that followed largely featured defensive derailing, belittling and accusations of oversensitivity. And to a person, these defensive harangers chose to distract from the fact that she was not complaining about the first question, only the follow-up question(s). Featuring the word "really. "
In a nutshell, when a complete stranger asks "where are you from?" - this is not an insult of any sort. And I cheerfully offer up my home town.
If they follow it up with - "but where are you really from" - that person is both insulting me and outing themselves as ignorant. And I do not tolerate ignorance but I won't rise to the bait of insults.
Because the key word is "really", although "no" and "but" can be added as fun intensifiers. It means a complete stranger is accusing you of lying, and denying you the right to self-identify, and asserting their entitlement to extra information to reinforce their prejudices.
My evolved response is to tell them my birthtown, and to end on a question "how about you?". I nod and smile at their answer and then turn away, walk off, or never return to their place of business.
Don't get me wrong, I'm glad that overt racism is no longer socially tolerated, so that bigotry has to invest in the joys of plausible deniability. But it's still alienating and distressing.