“Despite their long-term residence in different countries and isolation from one another, most Jewish populations were not significantly different from one another at the genetic level.”
This is pretty remarkable. Even if only 1 or 2 % of the Jewish population ignored the prohibitions against intermarriage, over such a long period of time, it would have made a pretty big difference.
It says a lot about the pretty extreme degree of isolation the community must have had over the long term.
I think DNA data is interesting in demonstrating affinity, but relating it to any particular land is nonsense. There is a certain chromosome passed from male to male that identifies members of the priestly family, Cohens and Levis, and it’s been found among an African tribe that claims to be descended from Jews. It does reinforce myth and memory and some of these people will rejoin their people eventually as have done some Chinese tribesmen in northern Burma, with the same traditions.
Jews have intermarried massively with every people on earth. We have in Israel whites, blacks, yellows and everything in between. People look exactly like the people they lived with for a few hundred years, whether it be Russia, India, or Ethiopia. We are not a race, but a community of shared common destiny, and it doesn’t matter where your ancestors came from, it’s what you wish to be. In the last decade we got in a whole bunch of Peruvian Indians who simply decided one day they wanted to be Jews and they are as welcome as anyone else.
Or one can call it "preserving the heritage".