no we're not told to ask about heritage/accent/what not, but you dont need to be told to do something to do it out of curiousity. "where are you from" was one of the first things we'd ask a noobie when he got to the unit.
anyway about the whole politically correct stuff, thats a bunch of bs. no matter what you say, its garunteed to offend someone somewhere, especially someone who is just looking to get offended (like alot of people who complain about politically correct constantly). not to sound harsh, but its life: its not fiar, its not worried about everyones feelings, and its not always nice. im not saying to go out and shout every racial slur you know, but you get the drift.
back to the main topic, yeah its a ****** thing to be asked. but unless you've served or you've had a friend that has already told u, most people dont know that its a bad question. i mean therse people that its not a bad question to, then again those are the ones that only sat on base during deployment.
kinda like randomly walking up to a vet in an airport and thanking him for serving: most vets that i know hate that.
sorry to sound harsh, but its a pretty normal question for someone not in the military to ask. generaly its not considered innapropriate.