Most of today’s “Greeks” are probably closer to modern Turks than Alexander & Aristotle’s DNA.
Almost every nation in Europe has Germanic/Nordic bloodlines because of the Barbarian hordes that destroyed Rome. Even though my mom’s family is Spanish/Basque, the blonde hair and blue eyes that runs deep in our family probably suggests Visigothic blood at some point way down in history.
Even in ancient times, the Ionian (e.g. Athens) and Dorian (e.g. Spartan) Greeks looked quite different on average, supposedly the former were swarthier than the latter. More Phoenician blood perhaps?
The Greek population was basically replaced by Slavs, like the rest of Eastern Europe, so I’ve read. Most of this mass migration of Germanics and Indo-Europeans occurred around the time of Rome’s fall, probably contributing quite a bit to it. The Huns are a notable example, but by no means the only one. Ostrogoths, Visigoths, Vandals, Lombards, a slew of others.
Those Visigoths romped all over a lot of Spain during and after the fall of Rome on an orgy of revenge against Rome.
My ancestors were Spanish-mostly Basques-who came to New Spain/Mexico in the late 16th-early 17th centuries and to what is now SW Texas and NM in the late 1700’s. Even with a generous helping of Native American over a couple of centuries, I’m one of several redheads with gray/green eyes in the family-we have some blondes, too-and most of us have medium olive skin.