Brithish American, African American, Chinese American, French American.....

I am very surprised with the reaction of denial that many people would when I ask their original nationality or heritage for the reason to start a topic of conversation.

In my dancing class, I asked a young man obviously a Russian American, who I think has natural talent of dancing ended up in his sensitive in mentioning heritage topic; as if it is a factor of fear to live in this country if you talk to a young people about their original heritage that will became a shame to their present life. People from all over the world immigrating to this country and being afraid others mention about their original heritage, the only thing they want people to recognize is they are American?

Who are American?

What's wrong of these people? Is it peer pressure make them fear of admit of their own heritage, which originally is wonderful beyond they think of themselves? Who make them feel guilty or shame about their own heritage?
Peer pressure from schools, media, working place, job opportunity?