Originally Posted by
Hahns
One hypothesis is that prior to the Slavic invasions the populations of Crete and the other islands were much more similar to those of the mainland, since those invasions would have had more of an effect on the mainland. I think that's logical and supported by the evidence.
On the other hand, there were other migrations which might have differentially affected the mainland, such as the Goths or even any northern shifted "steppe" group. Then, the islands, being closer to Anatolia, might have a bit more of that ancestry, although mitigating against that is the fact that there has been constant and continuing contacts between the islands and many parts of the mainland.
So, I'm waiting for the ancient DNA.
If you haven't already, you might want to take a look at the thread on the recent paper on Greek genetics. Just use the search engine to find it.