I think it goes deeper than certain people want to admit. It goes to show how even if you are a naturally born citizen, it takes more to be seen as American in our society. There are American passport holders all over the world with no connection to the country or the culture whatsoever. I’d assume the same goes for other countries even with multiethnic populations. If your parents or grandparents are not from America, it more than likely will show in your speech, mannerisms, style, other methods of expression. The Americanization typically happens in or after the teenage years but by then what’s taught at home is usually already ingrained to a degree. It’s no surprise that other Americans that aren’t first generation can sniff this out. It’s probably similar for any country with a history and populations that have been there for long spans of time.

Why people with recent immigrant history here in America pretend they aren’t still very connected to their ethnic groups while still retaining those cultures is disingenuous. This tends to be manifested a lot via interpersonal conflicts that take place within certain Latin American and Asian American individuals who are more than likely tend to be from very recent stock. With recent arrivals of various subgroups vs those that have already been through this rodeo, the “why am I not seen as” is exasperated.

Those would be considered fairly new arrivals. There are many Asian Americans that go back even further. For me, Chinese descent, it is 6 generations including myself. My 3x great grandparents and everyone since have also been US citizens.