Can You Tell Your Ethnic Identity From Your DNA?
The answer as to whether a DNA test can tell you your ethnic identity? Yes — and no.
We know that, when it comes to DNA, geography matters. Although in principle anyone can mate with anyone else, in practice we tend to mate with people nearby. If we could assemble all the DNA of everyone everywhere, we would expect to find that people living near each other were more likely to be gentically similar than people living farther apart.
In principle, then, it ought to be possible to compare the DNA of an arbitrarily selected individual with DNA from around the world to make a judgment of that individual's genetic origins. Direct-to-consumer ancestry companies offer just this kind of "admixture" test, and it is not uncommon for consumers to be told that they have a certain percentage of African, or Asian, or Native American DNA, for example.