> Genetics isn't everything, but it's an indicator that the populations have remained extremely stable (no large scale migrations) while the culture shifted under them.

This is why your comment is weird. You seem to be leaning on genetics a lot, when in aggregate, genetics are less than a rounding error for human behavior. Take a random human with random genes and drop them at childhood into another culture, and outside of that culture's reactions to them perhaps looking a bit different than the other kids, that person will grow up identifying with that culture.