Have you never seen one of those shows like "Who Do You Think You Are?" and such.

In it, it basically takes someone who swears black and blue they are "English, through and through" or whatever ethnicity, and after conducting genealogical tests, often show that the person who considered him or herself "(a particular ethnicity) through and through" are in reality descended from a number of different places/peoples.

My point is that ethnography can be a tricky thing, and just because a certain name has certain regional roots, does not definitely mean that people named as such did not migrate and move around the country/world at times.

And splitting hairs now, the fact that the generic "swarthiness" of Southern Italians is considered by some to have come from the Moorish influence, it could be arguable that "spaniard had the most influence by far", since Southern Spain was once also a bastion of the Moors. Ipso facto, the Moors could arguably be considered to have had more of an "impact".

Theres a kind of logic behind the somewhat racist saying "Africa starts south of Rome"

I echo George De Stefano's opinion; for me, thats where Italy starts.