I have mixed feelings about the commercial projects to analyze snippets of DNA from volunteers to give them feedback on their "ethnicity", where they come from and who they are related to. There is a clear network effect in this, so that once you get up in the thousands of customers, you will be able to uncover lots of interesting data. But this will mean that more and more people will join up with one or a few of these databases, and then the risk factors set in. Once joining one of them becomes commonplace, people will start discovering the extend to which their actual DNA heritage differs from the official records. You will start running into cousins who don't share any close ancestry, and lawsuits will break out. More rarely, a married couple may find out that they are close relatives, if they come from the same area. Perhaps it would be better to let buried dogs lie.