I'm not sure what you think is wrong with that study. It's not self-evident that the people who live in a place now are descended from people who lived there thousands of years ago, since people migrate, get displaced, die out, etc. For example, most of the people living in Egypt today are probably not descended from the Ancient Egyptians.
That’s right because they had Angela Merkel borders
BWAHAHAHAHA
It is just a wee bit surprising for the reasons you mention.