This whole paper is amusing to me because I remember davidski claiming just a few weeks ago that genetically Mycenaeans would appear just like the steppe individuals. If anything it leads me to believe they came from the east.
Why would the Mycenaeans be closer to Sicilians than modern Greeks though? The inhabitants of Magna Grecia mixed with the native inhabitants of the Sicily itself when they first colonized, they even considered themselves a new people, and the island has been home to everyone from the Carthaginians to the Normans. That would mean mixing with the Sicels changed very little and then they remained the same for the next 3000 years while Greece failed too.
One factor might be that the mainland Greeks, particularly in the north, received some ancestry from the migration of the Slavic tribes. The Italians got virtually none of that. Northern Italians and Tuscans did get some Celtic and some, if less, Germanic, the prior before the fall of Rome, in the first millennium BC, and the latter after the fall of Rome, but much less of it got to places like Sicily. In fact, I think a good percentagae of what they did get was mediated through the Romans, perhaps, and then the "Lombards", i.e. northern Italians from Lombardia and Liguria and some from Piemonte, as well as from the native "Italic" tribes, who might not have had all that much "steppe" by the time they got to Sicily. I mean, look at the "steppe" percentages in Bronze Age Iberia, even with all that R1b. The small percentage from the Muslim invasions in Sicily and perhaps infusing a bit into far southern Italy didn't change things very much, apparently, at least that's what it looks like to me based on the NA percentages autosomally.
We won't really know if we're totally on the right track, however, until we get ancient dna from Italy. That will trump any speculations based on PCAs, modern proportions etc. I don't mean to imply otherwise.
I've been saying since I was on dna forums and then on 23andme and then here that all that "West Asian" in southern Italy and Sicily did not come with the Muslims. The folk migration to Sicily was from North Africa, and we know how much North African they have. The "Arabs" were the very thin layer at the top, the elites. We'll have to see what the ancient dna from Italy tells us about what Bronze Age and Magna Graecia southern Italians were like.
There's also been a lot of ******** and mythology on the internet about southern Italy/Sicily. The Normans were under 100 men at arms when they arrived. How much autosomal change could they have brought? The Carthaginians had two small emporia in northwestern Sicily, no presence at all on mainland southern Italy. It wouldn't matter to me in the least if southern Italians had a lot of this ancestry, but I still believe that major autosomal change comes from large folk migrations which does not describe these people at all.
I don't know what the ancient dna will show for Italy, but it seems pretty clear that Iberia and Greece don't fit the same pattern as central and Northern Europe. How could they? It's very different when you move into virtually de-populated places or where the "natives" have experienced lots of disease and debilitation from repeated crop failures due to either degradation of the soil and/or climate change?