The idea that a person in America is "1/8th Irish" or "1/4th Russian" is a fallacy, and people rarely do that once they are old enough to understand how illogical it is to say such things. There is justification if your parents are native to another country, or even your grandparents, but beyond that, you are an American through and through. Personally, I've only experienced others mentioning what state they are from. Are you from the south? The north? East coast, west coast, so on and so forth.