Well, regarding the migration patterns...we only know so much.

Some Indigenous people migrated into North America from the Arctic. Others migrated into what is now the United States from South America and/or Latin America. It begs the question: how far back is "what counts"?

And if I was getting to know someone as a friend, I might eventually feel comfortable enough with them to ask them about their ethnic heritage...but I'd probably word it in a deliberate way, such as, "Have you ever had the opportunity to trace your family tree?"