An interesting story has appeared in Science magazine, followed by a synopsis in the LiveScience web site. While several companies now claim that for as little as $100 and a swab of the inner cheek, they can reveal a person's family tree and ancestral homeland. However, more than a dozen scientists from various backgrounds say such "recreational genetics" or "vanity tests" have significant scientific limitations and rely on misconceptions about race and genetics.
"If a test-taker is just interested in finding out where there are some people in the world that share the same DNA as them, then these tests can certainly tell them that," said Deborah Bolnick of the University of Texas in Austin. "But they're not going to tell you every place or every group in the world where people share your DNA. Nor will they necessarily be able to tell you exactly where your ancestors lived or [what race or social group] they identified with."
A common misconception about genetic ancestry testing, Bolnick said, is that it can reveal information about an individual's ancestry. It cannot.
The article does not dispute all DNA testing for genealogy purposes. Instead, it basically says, "be aware of what you are purchasing." You can read more at http://www.livescience.com/health/071018-vanity-tests.html.