I signed up with the 23andme DNA service, just for fun, and discovered that my paternal DNA Haplogroup is G2c. Here’s what Wikipedia tells me:
The most plausible scenario for the spread of G2c within Europe is an origin among Jews in Sicily, and a spread northward to Germany and the Polish-Lithuanian Commonwealth at the time of the expulsion of the Jews of Sicily in 1492.
It is estimated that Jews made up 6% or more of the population of Sicily in 1492. Historical evidence shows that most Sicilian Jews went eastward to the Ottoman Empire, where Sicilian Jewish congregations existed in Salonika and Constantinople until the late 19th century. However, it is known that many Sicilian Jews first went to Calabria, and then Jews were expelled from Calabria in 1524, and later from the entire Kingdom of Naples in 1540. There was a gradual movement throughout the 16th century of Jews in Italy from south to north, with conditions worsening for Jews in Rome after 1556 and Venice in the 1580s. Many Jews from Venice and the surrounding area migrated to Poland and Lithuania at this time.
In this scenario it may be that there was a direct migration from Sicily or Southern Italy separately to both Western Germany and Poland-Lithuania, but the presence of G2c in Germany may be due to a later migration from Eastern Europe to Germany starting with the aftermath of Khmelnytsky’s Pogrom in Poland in 1648,
Jews had lived in Sicily since Roman times. After the Byzantine reconquest of Sicily from the Arian Ostrogoths who were very tolerant of the Jews in 552, conditions worsened dramatically for Jews in Sicily. Under the Byzantine Empire few Jews lived in Sicily because of official persecution. Before 606 the bishop of Palermo ordered the synagogue to be converted into a church. An edict issued by Leo III the Isaurian in 722 which ordered the baptism by force of all Jews in the Empire. After the Muslim conquest of Sicily in 831-902, large numbers of Jews settled on the island. In 972, the Arab merchant Ibn Hawqal mentioned a Jewish Quarter in Palermo, and by 1170, Benjamin of Tudela reported 1500 Jewish households in Palermo and 200 in Messina. In 1149, Roger II forcibly brought the Jewish brocade, damask, and silk weavers of Thebes in Greece to Sicily to establish a silk industry there. This is an example of a late entry into Sicily of non-Iberian, non-Provençal Jews from outside of Western and Central Europe, from a region that has been poorly tested or devoid of Jews in modern times.
The preliminary conclusions from this evidence is that haplogroup G2c is not native to Europe. The very late tMRCA, and the very high ethnic specificity indicate a rather brief presence in Europe, but one that participated in the exponential growth of the Ashkenazi Jewish population in Eastern and Central Europe after the Black Death. The complete lack of G2c in Iberia and also so far among Spanish Jews indicates that G2c didn’t come from Spain, or France, since some Spanish Jewish families originated in southern France and migrated to Spain after France expelled the Jews in 1306. This, along with the other evidence, leaves Sicily as the European origin of G2c. We know that Greek and Mizrahi Jews arrived in Sicily as late as 1149,and that primarily most Sicilian Jews settled there during the Arab Emirate of Sicily. This is one way of explaining the very late presence of G2c in Europe, the likely presence of G2c among at least Kurdish Jews, if not other Mizrahi Jews as well.