It works every time. Regardless of how often I get asked, every time someone new asks it, my brain locks up. Usually I pause long enough that whoever is asking feels the need to ask it again.
I have no place of origin. I am an American. I have moved so often that where I have lived has had almost no relation to the kind of person I am, or the customs I keep dear. My place of birth is not the answer they want. Born in New York City, moved away before I was even a year old. I am not a New Yorkan.
Nowadays I find it easiest to simply tell the inquirer that I joined the Navy from Colorado. This satisfies nobody, however. I need to come up with a better answer. They will usually push and pry some more, and I will tell them not only where I was born, but will give them an itinerary of every place I have lived. This can take a while.
And still, this rarely satisfies anyone. The color of my skin does not betray my nationality, nor do my major features. Nor should they. Not even I am sure what I am. I know there's some black, hispanic, and Danish in me. I also know there is more than that. I have been called black, caucasian, hispanic, and even once someone thought I was asian.
Race confuses me. And so does the 'where are you from' question.
I don't think I'll ever figure it out.