[SJackson]

The use of the term “Jews” here is not appropriate, since they are talking about genetics....All of the “Italian” surnames that end in an O are originally Jewish immigrants

I certainly agree with the first part. This ancestry prowling through DNA is interesting, but imo meaningless. I wonder what other northern European groups share the same genes. The "o" thing I've not heard.

[editor-surveyor]

The “O” ending thing is not 100% reliable, except in Scicily, where it seems to run pretty strong.

It has never been an ‘advertised’ thing, but it is fairly common knowledge within the families.

[editor-surveyor]

P.S.

The same thing sort of works in Romania. I have a friend who is a Romanian immigrant, whose name is Vianu, and he tells me that it is about the same there, except with a U instead of the O. He is a practicing Jew, but his family in Romania shunned their ancestry, and attended a Catholic parish.