This is actually the point of the thread, I believe, which is for people like Azzurro/Principe to appropriate Jewish identity. He believes in a religion run by a Calabrian rabbi.
He left this site because the absurdity of a lot of his claims was pointed out. Of course there was some gene flow from Jews into Italians, and vice versa, at least until Draconian laws against intermarriage were instituted.
When the Spaniards took over control and brought in the "Holy" Inquisition and started expelling Jews from Southern Italy, I'm absolutely sure, and there are documents to show it, that some Jews converted and remained. That kind of event isn't, however, going to fundamentally change the genetic signature of a people, although it may make some changes around the edges. Sicily, likewise, was under Muslim rule for two centuries. Yes, most of them were exiled under Frederick II. Does that mean some didn't escape the net, especially if they had been long resident on Sicily and had assimilated centuries before.
That's why the Iberian attitude toward this is difficult for me to understand. I know of many books by Italians on the Muslim occupation and its impact on Sicily, and while obviously the conquest and death, the discrimination is criticized, the many benefits they brought to the island are also acknowledged. I have yet to find one written in Spanish about Spain. I guess it depends what you're taught in school, or how your national "myth" is framed. Personally, I may believe that the Langobardian influence on Italy genetically is overblown, especially looking at y dna lines, but it exists, and so does the cultural impact, whether I like it or not.
What I don't like in particular is all this "ethnic" appropriation that is going on, and the different rules for different groups, and the mania for finding more "exotic" ancestry in certain groups than exists, ancestry that is found not necessarily in academic papers but in their own modeling.
Well, we know how that worked out with the Etruscans.
Historians and Archaeologists should never be discounted.
I still don't understand Davidski's gripe, however.
What does he care how similar Greeks and Jews might be?
Parenthetically, those Southern Jews from whom some confused Italians or pretend Italians want to claim descent are not Ashkenazim, who formed from an amalgam of different groups. I guess the closest you could come is to say they're sort of Sephardi in some way.