Tracing Jewish genetics

The single most hotly debated (and often heartbreaking) issue of Jewish identity is whether and to what extent we carry our Jewishness in our blood. It’s a question that took on life-and-death implications during the Spanish Inquisition and again during the Shoah, but it still arises in Israel today when it comes to whether a man or woman is entitled to be married there or to be buried in a Jewish cemetery.

For Harry Ostrer, a professor of pathology and genetics at Albert Einstein College of Medicine, it is question that can be answered by the science of DNA, as he explains in “Legacy: A Genetic History of the Jewish People” (Oxford University Press: $24.95).

“It was my effort as a medical geneticist to bring the benefits of contemporary human genetics to my own people and to understand my Jewishness,” he explains. “For me, the work with various aspects of Jewish genetics provided a new framework for thinking about Jews.”

Yet Ostrer himself acknowledges that early reports of his work in Jewish genetics prompted a fierce and combative response in some circles. One commentator, for example, declared that “Hitler would have been pleased by our findings.” Indeed, Ostrer’s stated purpose in recasting his scientific research into a book for a general readership is to “tone down the debate into a more thoughtful realm.”

The story begins with the observation that certain diseases seemed to occur more often in Jewish patients, an issue that was investigated in the early 20th century by anthropologist Maurice Fishberg. He found that diabetes was not “a racial disease” — contrary to the belief of some German doctors who called it Judenkrankeit, that is, a Jewish disease — but he pointed out that the condition then known as “amaurotic family idiocy” (now known as Tay-Sachs disease) “occurred almost exclusively among Jews.”

Fishberg, as it happens, suffered from many of the same misconceptions that have always plagued the subject of Jewish identity, including the notion that someone can “look Jewish.” He also concluded that “Jews were not a pure race but a racial composite, having mixed with surrounding populations during their long history,” a statement that hints at scientific truth, even though it relies on the unfortunate terminology of race. Fishberg had glimpsed something that Ostrer would later prove: “ ‘Looking Jewish,’ ” explains Ostrer, “should reflect the common geographic origin of contemporary Jewish people with evidence of a shared genetic legacy among themselves.”

While it is treacherous to treat the Bible as a work of history, it is true that the Jewish population of ancient Israel was dispersed by various foreign conquerors. Over two millennia of exile, the Jewish genetic profile came to include an “admixture with other populations,” as Ostrer writes. Diversity, rather than purity, is a fact of Jewish identity, both culturally and genetically. But Ostrer wanted to know if some genetic evidence links a contemporary Jewish man or woman to the Jews of biblical Israel.

The answer, as it turns out, is yes. He acknowledges the differences in various Jewish communities — Ashkenazic, Sephardic, Iranian and so on — but he points out that Jews around the world share a genetic heritage that points to a common point of origin in ancient Israel. “All of the populations, with the exception of the Indians and Ethiopians, had mitochondrial genomes that were of Middle Eastern origin.”

Some of Ostrer’s surmises are truly shocking.  He argues that the dating of genetic mutation “provid[es] to genetics what carbon dating has provided to archaeology and paleontology,” and suggests that the increased risk for breast and ovarian cancer, Parkinson’s disease and hemophilia entered the Jewish genetic profile during or shortly after the reigns of David and Solomon.

On the yearnful aspirations of contemporary Jews who regard themselves as lineal descendants of David and Solomon, however, Ostrer is less encouraging. Indeed, he characterizes the effort to find a “Davidic Y-chromosomal lineage” to be “a flop.” And he warns that the search for one’s origins is not always an uplifting enterprise: “Some men will walk taller when they learn about shared ancestry with the Cohanim,” he warns. “Others will be surprised to learn about their ancestral skeletons in the closet.”

Ostrer acknowledges the sharper edges of the debate in Israel and the Diaspora over “who is a Jew” and what it means for the future of the Jewish people and the Jewish state. But he insists that it is wrong to assume that Jewishness is essentially self-defined as a religious or cultural affiliation. “The evidence for biological Jewishness,” he insists, “has become incontrovertible.”

“[T]he Jews can be said to be a people with a shared genetic legacy,” he sums up, “although not all Jews share the same genes, nor is having part of that legacy a requirement for being Jewish.”

Ostrer approaches the whole subject from a scientific stance, and he has something provocative but also important to say to any reader who has wondered about what it takes to be an authentic Jew. But there are some other consequential implications to his assertion that Jews carry “a 3,000-year genetic legacy,” if only because it soundly repudiates the claims of Ahmadinejad and his fellow thinkers in the Muslim world that Jews are only newcomers and interlopers in the place that was the site of biblical Israel.

Jonathan Kirsch, author and publishing attorney, is the book editor of the Jewish Journal. His next book is “The Short, Strange Life of Herschel Grynszpan: A Boy Avenger, a Nazi Diplomat, and a Murder in Paris,” which will be published in 2013 under the Liveright imprint of W. W. Norton to coincide with the 75th anniversary of Kristallnacht. Kirsch can be reached at books@jewishjournal.com.