Yeah, of course the math makes sense but one can clearly find pockets of people it likely doesn't apply to. And for sure, trying to point to specific ancestors isn't really possible you don't even need to go back 12 generations in some cases if memory serves.
My main point is that its becoming clear that many supposedly very isolated populations have in fact had gene mixture with outside groups in the not distant past and that there were large pre-modern migrations and mixing events.
If I'm recalling the numbers correctly, there's somewhere between a one in a million and one in a billion chance of not inheriting any DNA from one of your grandparents -- unlikely, but not so unlikely that there aren't dozens or hundreds of people walking around for whom that is true.
My main point is that its becoming clear that many supposedly very isolated populations have in fact had gene mixture with outside groups in the not distant past and that there were large pre-modern migrations and mixing events.