[stickfigure]

This seems a poor way of economizing on tests. How would someone of (say) German descent be sure that some of their ancestors didn't come from across the border? Very few people can trace their lineage back more than a couple generations.

[troupe]

Keep in mind there is also the chance of false positives on those types of tests. So anything you can do to do them only on people where there is a higher chance of them being meaningful saves not just the cost of the tests but mental anguish for people who would get the false positive results.

[rubyist5eva]

I agree, it's not an exact science and I am not a doctor or run a practice so I do not know why they would do it this way. Probably a "best we can do" type situtation.