We Are One, Genetically
The Jewish communal world is obsessed with the notion of peoplehood and how to define it, promote it, strengthen it — especially how to encourage younger, unaffiliated Jews to feel part of a sprawling but interconnected global family. A new scientific study may offer some help.
Turns out that Jews the world over share many genetic traits that are distinct from other groups and date to ancient times. We are, said Gil Atzmon, an assistant professor at Albert Einstein College of Medicine and the study’s lead author, “identical by descent.”
Researchers have already shown the prevalence of, say, a Y chromosome shared by many kohanim, but Atzmon said that his study — published June 3 in The American Journal of Human Genetics — may be the most comprehensive study of genetic linkage to date. It examined three major groups of Jews in the Diaspora: Ashkenazim from Eastern Europe; Sephardim from Italian, Greek and Turkish ancestry, and Mizrahi Jews from Iraq and Syria. Participants were recruited from the New York region, Seattle, Athens, Rome and Israel, and must have had four grandparents from the same Jewish community.
The study did find some of what researchers call “admixture,” the mixing of Jewish genetic markers with those of non-Jews, through intermarriage and conversion. Still, “the Italian Jew is closer to the Iraqi Jew than to his Italian neighbor,” Atzmon told the Forward.
Scientifically, these findings are significant because they provide a context to further study the genetic origins of disease. While there are other people with genetic similarities caused by geographic isolation — the Amish and Sardinians are two examples — the Jewish genetic connection goes beyond geography, enforced by centuries of cultural and religious isolation.
Among Jews concerned about continuity, which these days means just about anyone in communal leadership, the findings of this study raise an uncomfortable question. If a similar genetic structure bound Jews together for centuries, provided concrete evidence of a tribal connection, of peoplehood, what will happen in the free-for-all that is America? “This is a very delicate question,” Atzmon acknowledged. “Assimilation can dilute the genomic sharing among Jews. It can take a couple of generations, but [at some point] the genomic is shuffled so much, it can’t be recognized.”
In an age when exclusivity is frowned upon and multiculturalism prized, some Jews may celebrate if the genetic distinctions fade away and are replaced by a more pluralistic definition of who we are — or at least, who our genes say we are. But breaking down the cultural and religious isolation that has characterized Jewish life since ancient times also contains risks. Science tells us that we have, indeed, been one people. Will we remain so?