Who are the Jews? Where did they come from? What is the connection between an ancient Jewish priest in Jerusalem and today's Israeli sunbather on the beaches of Tel Aviv? These questions stand at the heart of this engaging book. Geneticist David Goldstein analyzes modern DNA studies of Jewish populations and examines the intersections of these scientific findings with the history (both biblical and modern) and oral tradition of the Jews. With a special gift for translating complex scientific concepts into language understandable to all, Goldstein delivers an accessible, personal, and fascinating book - the first to tell the history of a group of people through the lens of genetics. In a series of detective-style stories, Goldstein explores the priestly lineage of Jewish males as manifested by Y chromosomes, the Jewish lineage claims of an obscure black South African tribe, the differences in maternal and paternal genetic heritage among Jewish populations, and much more. The author also grapples with the medical and ethical implications of our rapidly growing command of the human genomic landscape. The study of genetics has not only changed the study of Jewish history, Goldstein shows, it has altered notions of Jewish identity and even our understanding of what makes a people a people.