Angela, i am sure that if we had more samples from southern Greece, Peloponnesus for example, they would also overlap with the Mycenaean samples as presented on the PCA for the Sicilians and the Ashkenazi Jews. What's your thoughts on this? The Greek samples are not very varied to give an accurate picture, since most come from Thessaloniki (Macedon) and Crete. It is a known fact that Sicilians are very close to Peloponnesian Greeks. Just as an example have a look at this PCA taken from the "
Genetics of the peloponnesean populations and the theory of extinction of the medieval peloponnesean Greeks,
https://www.nature.com/articles/ejhg201718" study, which shows the Peloponnesian Greeks overlapping with the Sicilians.
Postscript: I didn't read all of the thread, but i did go through many pages. Don't know whether you already gave an answer to this.
I am afraid that this study is a failure since it compares the modern Greeks with populations such as Belorussians, Polish, Ukrainians and Russians to determine how much "ancient Greek" or "Slavic" modern Greeks are!
In order to do such an experiment, your assumption that the Slavs that came to Greece in the Medieval were like the modern Belorussians or Poles, must shift to an assumption that the proto-Slavs who started migrating from Central and Eastern Europe towards the Balkans, must have absorbed and accumulated a lot of foreign blood and with that regard a native Balkan, such as a Dacian or a Thracian who happened to be on their path to Greece.
We do have native Iron Age Balkan samples such as Iron Age Bulgaria
I5769 and Iron Age Scythians from Moldova such as scy300 and scy305 who happen to be way more similar to the available ancient Greek samples than to modern Poles or Belorussians!
We can observe this phenomenon in every study until now, we have a study for Lombards, Visigoths or Avars and many of them were of mixed origins and yet they were united under a single culture because it is not the genetics that united them but the culture they accepted!
As such, many modern Greeks been close genetically to Sicilians doesn't mean much unless there is an alternative way such as comparing the y-dna and mt-dna markers or IBD sharing that can prove the kinship of the populations in question and of course, assuming that modern Sicilians are descendants of the ancient Greeks.
Now, we have here too many assumptions so we better skip the Sicilians altogether and compare the modern Greeks directly to the ancient ones for better results!
Unfortunately, we don't have many Greeks here who post their genetic results unlike others.
For example, we actually have a dozen of ancient samples to which we can actually compare our DNA directly using some helpful tools such as Gedmatch!
Comparing my own DNA, I have found out that I share the most DNA and segments with an ancient sample from LBK Stuttgart which was a Neolithic, farmer like sample!
Now, this is not a big surprise since this sample happens to be a very good match for a lot of people, you can check out this very useful blog:
https://dna-explained.com/2014/10/04/more-ancient-dna-samples-for-comparison/
Now, when I try to compare my DNA with ancient samples from the Balkans, the best match for me is an Iron Age sample from Bulgaria,
I5769, with who I share a total of 7.8 cM with the largest segment being 3.9 cM long!
I also share a DNA with the Bronze Age samples from Dalmatia, I3313 and I4331, the Bronze Age sample from Bulgaria, I2163 and the two "Avar" samples from Hungary, AV1 and AV2!
Interestingly enough, I don't share a DNA with the available ancient Greek samples on Gedmatch such as the Mycenaeans and the recently added Classical Greek from the Iberian colony of Emporion, I8215!
To me, this is very logical and trustworthy because if it was just a coincidence, how come I share DNA with ancient samples who actually are of relevance for the history of the Balkan people?
How come I don't share DNA with Germanic, Iberian or Collegno samples if it was just a coincidence?
The y-dna and mt-dna markers are also of great importance and so far all ancient Greek samples had turned out to be J2a albeit we need much better resolution than simple designation such as J2a!
But even then, modern Greeks are only around 20% J2a in terms of y-dna!
As you see, once you open the Pandora's box, you will find that there are so many if's, and it's not that easy as a simple two dimensional PCA plot or admixture comparison based on TSI, IBS or other imaginary admixture components, to determine what those scientist tried to do!