Genetic research can open book on Jewish identity — for good and bad

Father William Sanchez wears a Star of David pendant on the same chain as his crucifix, and he keeps a menorah in his parish office. After a DNA test confirmed his Sephardic roots, the Albuquerque priest has been actively reconciling this discovery with his Catholic beliefs.

“Knowledge of my Jewish ancestry has provoked me to question things, yes,” Sanchez says in the book, “Abraham’s Children: Race, Identity and the DNA of the Chosen People” by Jon Entine (Grand Central, 2007).

Looking back over his childhood in New Mexico, Sanchez now recognizes the Jewish signs: his parents shunning pork, spinning tops during Christmas and covering the mirrors at home if someone in the family died.

For Crypto-Jews like Sanchez, DNA testing services can confirm or disprove suspicions about a hidden Jewish family history, uncover unknown genetic disease risks or inspire greater exploration of Judaism. For small populations in Africa and Asia, genetic research has shed light on claims of Jewish ancestry and provided a better understanding of Jewish migration over thousands of years.

But critics fear that Jewish genetic research also opens a Pandora’s box. The discovery of a shared genetic marker among men who claim to be descended from Kohanim grew into wild, exaggerated claims in the media that geneticists had confirmed the story of Aaron. Some have decried research exploring a genetic basis for Ashkenazi intelligence as politically incorrect and racist, since all humans are 99.9 percent similar.

Entine, who will be speaking at Adat Chaverim and Brandeis-Bardin this weekend, believes exploring that .1 percent is worth getting researchers riled up.

An American Enterprise Institute fellow and former NBC news producer, Entine is no stranger to controversy. He tackled the topic of race in sports with “Taboo: Why Black Athletes Dominate Sports and Why We’re Afraid to Talk About It” (PublicAffairs Books, 1999), which was lauded by Scientific American as a “well-researched, relatively thorough and lucidly written case.”

After “Taboo” was published, Entine learned his sister had breast cancer. As a teenager, he had lost his mother, grandmother and aunt to cancer over a period of three years. The family assumed it was a coincidence at the time, but recent genetic testing revealed the BRCA2 genetic mutation contributed to his sister’s cancer.

Since Entine has a young daughter, he decided to undergo testing, which confirmed he carries the mutation. The experience inspired him to research the link between Jews and DNA.

The result is “Abraham’s Children,” a survey of Jewish genetic research paired with a chronicle of Jewish history that explores the thorny question: “Who is a Jew?”

Entine writes that Jewishness is a function of religion and ancestry, shaped by faith, politics and culture. Given the Jewish community’s historically insular nature, most Jews also share genetic markers, which speaks to common ancestors.

This commonality inspired research in the 1990s that found the Cohen Modal Haplotype, a set of six identical genetic markers shared among Ashkenazic and Sephardic Kohanim, passed from father to son on the Y chromosome, which doesn’t change much over time and may have originated with a common ancestor. While the genetic markers alone do not prove the existence of Aaron, they can be seen to confirm a biblical tradition.

The haplotype, however, is also not unique to Jews — Kurds, Armenians, southern and central Italians share these same markers but to a lesser extent.