It confirms much of what readers of this blog have seen posted here repeatedly. It's so good, it's worth quoting at length:
The genes that make you a superfast runner or that identify you as Irish are less well-studied. The accuracy of any one test depends on the data your DNA is being compared to. One 2009 journal article said consumer DNA tests were akin to horoscopes exploiting the human tendency to hunt for patterns in meaningless data.
So what does it mean when a test says I’m 25 percent Irish?
Meanwhile, in Slate, appeared another excellent piece by John Edward Terrell. Here's the quote for you to read for yourself: