Although they probably weren't named Sarah, Rebekah, Rachel and Leah, four Jewish "founding mothers" who lived in Europe 1,000 years ago have been credited with being the ancestors of nearly half of all Ashkenazi Jews, who constitute the majority of the current Jewish population. About 3.5 million people - or 40 percent of Ashkenazi Jews currently alive - are descended from these matriarchs, who were among a small group, probably after migrating from the Middle East, according to the Israeli researchers, who also provide evidence of shared maternal ancestry between Ashkenazi and non-Ashkenazi (Sephardi and Oriental) Jews. The studies that...