Jewish communities in Europe and the Middle East share many genes inherited from the ancestral Jewish population that lived in the Middle East some 3,000 years ago, even though each community also carries genes from other sources — usually the country in which it lives. That is the conclusion of two new genetic surveys, the first to use genome-wide scanning devices to compare many Jewish communities around the world. A major surprise from both surveys is the genetic closeness of the two Jewish communities of Europe, the Ashkenazim and the Sephardim. The Ashkenazim thrived in Northern and Eastern Europe until...