I suspect that, for Erdrich, the tribe protested (she confirmed this), but the motive may have been (which was not really stated) that they might have been concerned that if they weren't shown to be native enough
(whatever the hell that means), they could lose certain privileges. Anyway, that's my take on that.
I'd welcome the DNA testing.
Plus I think he should do a show just on Jews, or on other relatively small and insular populations (the Amish? Relatives of the Shakers?). I'm quite sure that my husband and I are cousins within that 250 year window they looked at, seeing as we are both purely Jewish (e. g. no intermarriage) back at least to great-grandparents and most likely further, and from not too terribly far away parts of Europe. Hell, most Ashkenazi Jews probably fit together into that window.