“Oh. He’s an American.”
We might see the persistent refusal to accept ‘I’m an American’ as a recognised nationality, at least on their home front, as a consonant reflection of their mixed and matched heritage. However, it does present them with inconveniences.
If an American asks another American his nationality (like asking here in Cayman ‘who you for?’), and he replies, “I’m an American,” what does the other person say? It’s, “Oh, come on, tell me, really, what are you?”
The reply is, “I just told you! I was born and raised in America.”
“No, no. I mean, where did your parents come from?”
“Well. My mother was born in West Virginia.”
“Where did your father come from?”
Now, the person is stumped. Finally he has to admit. Poland? Ireland? Etc. Etc. And what does the pouncing interrogator reply?
“Oh, so you’re (Irish).”
We British, when we discover who you are, say in a tone that intimates at least a slight reprimand, “Oh, so you’re an American.”