America, I'm looking at you.
Now don't get me wrong, there is nothing wrong with acknowleging your ethnic or cultural background, there is something wrong with wearing it like a badge, or just plain expressing it stupidly.
The attempt at middle ground by using both cultures just comes across as silly (eg african/irish/italian-american). If you were born in America - that is your nationality. It is also where you are from. You are not from wherever your parents are from. You have cultural ties there and, perhaps, ethnic roots there. But you are not from there.
It is of cource an identity issue. "I'm with that group, see? I have 'my people' now" is the gist of it. Its more prevalent in immegrant cultures like the states, because I guess it helps to feel like there are "your people" around.
I think an Indian girl at my University put it best: "My parents came over on a boat, I grew up watching Bollywood movies, but I'm British, its just my cultural herratage is Indian. Which is pretty cool."
She spoke two dialects of "Indian" (I forget which) before she could speak english properly. But she understood the difference. She identified herself as British because thats what she knew, and where she was born. Its a basic language issue really. There is a difference between nationality and cultural or ethnic background.
Saying "I'm German/Irish/African" is, unless you were born there, just wrong. You are not. No more than I'm a Viking because many many generations ago I had family there. You could get away with Celt, because that describes ethnicity and so instantly tells the other party what frame you are referencing, but where you are from is where you are born. Unless you answer "my parents" because thats correct too.
If you chose to identify with a specific culture in your family background then thats great (say... mexican, or brazillian), but you are not Mexican/Brazillian. You never will be. Sorry. Its about language, and I'm a bit of a tart about language, it needs to be used correctly.
Again, let me say: There is nothing wrong with identifying with a specific culture in your family history. Thats great. But you are not from where that culture is. Its a semantic issue, but semantics means meaning, so semantics are important. Without meaning there is no point to language.
In this case the language is being mis-used and in a dividing manner. Its adding a group mentality to things where they aren't needed. Its amazing what a difference a few words can make.