Using a DNA test to determine your ethnicity

I’ve read threads on this board that said that different races weren’t statistically genetically different from each other. If this is true, then what is going on with the tests that this site http://www.familytreedna.com/description.html is offering?

How accurate can such a test be? What are the chances of unrelated people from two different races having the same Y chromosome?

These tests aren’t looking for genes that determine the ethnicity or appearance of a person, they are looking for specific features that are known to be peculiar to a known ancestral lineage - it would be possible, for example, to test for certain genetic features that are known to exist in family trees originating in, say, France - this doesn’t mean that the features themselves are what make people French (so if you spliced the sequence into the genome of an American, he wouldn’t suddenly develop a Gallic Shrug and a penchant for soft cheeses), the features just happened to originate there.

Ah, It seems that I misremembered what those original threads were about. I guess I’ll have to pay up so that I can search again. Thanks Mangetout.

There have been cases where these tests have resulted in identifications directly opposed to individuals’ self-identifications based on family tradition, culture, and physical characteristics. I’d have to hunt for a cite, but one person who had called himself black all his life, and certainly could trace some of his ancestry to African-Americans, turned out to have entirely European and Asian genes. Somewhat to his surprise. He ultimately decided not to change his self-identification. Not at all to my surprise …

Proving the adage, “Once you go black…” :smiley:

Yea, if you can find an article on that story, please post it here. The tests didn’t show any African genes at all? I know people that appear to be of one race only, when they are actually biracial, but never of a person that displays characteristics of a race that they’re not even a part of.