"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.
Jewish genetic testing is also being used to better understand historic Jewish migration patterns. For instance, the Lemba, a southern African tribe that claims a longstanding Jewish heritage, were found to have Semitic genetics, including the Cohen haplotype. While their connection doesn't trace back directly to biblical Israel, their genetic heritage does seem to have a basis that likely originated with Diaspora Jews.
Entine argues, however, that DNA alone is not a basis for Jewish identity, and that the Jewish romance people have built up about what the Y chromosome or the mother's mitochondrial inheritance represents is only a tiny sliver of the overall genetic makeup.
For the Lemba, the 22 pairs of nonsex chromosomes, known as autosomal DNA, "is definitely African," Entine said, and the tribe's members are still expected to formerly convert if they wish to be recognized by Israel as Jews, much like Ethiopia's Falash Mura, who were found to have no Semitic DNA.
Despite Entine's use of "race" in the subtitle, a concept most genetic researchers no longer use and Jews abandoned after the Holocaust, he believes Jews are and have always been a tribal people, whose genetic diversity has grown over time through conversion and marriage.
"There's no question that Jews historically have been a people, and it's more than just a culture, and it's more than just a religion. Judaism was founded as a tribal religion. It was never just about faith," he said.
While the other geographically focused tribal religions died off, Judaism survived and became a major world religion, birthing two faith-based religions -- Islam and Christianity, he says. "There's all kinds of rigmarole we have to go through that enforces a kind of peopleness on us, everything from the gauntlet you have to go through to understand and accept Judaism.... So there's always been an ancestral dimension to Judaism."
More important than identity, Entine says, are the medical dimensions of what Jewish DNA research represents.
Entine says the genetic insularity of Ashkenazim makes them an ideal group for medical research. While Ashkenazi DNA is believed to be a mixture of Middle Eastern Jews, Khazarian pagans and Christian converts, he says, the walls went up around the community about 1,000 years ago. Ashkenazi Jews had the lowest historical intermarriage rate of any culture, estimated a roughly .5 percent, which ensured that their genetic markers remained mostly unchanged.
The BRCA2 mutation present in Entine's family line represents one of more than 40 different genetic disorders that affect Jews. "The discovered differences can now be a matter of life and death," he said. "The fact is the medical research is so important, and there's so much desire to challenge our mortality that people are going to be focusing on our medical differences."
When his 10-year-old daughter turns 18, Entine would like her to go in for genetic tests. He believes the information could be used to aid her with early detection and possible prophylactic measures that could save her life.
"It's such a powerful, single-gene mutation that it's information she could productively use in her life," he said.
Jon Entine will speak with Adat Chaverim on Dec. 13, 2-4 p.m., at American Jewish University, 15600 Mulholland Drive, Los Angeles. $10 (students, seniors and Adat Chaverim members), $12 (nonmembers). To register, call (818) 623-7363. Entine will also speak at "A Day of Archaeological Insight" on Dec. 14, 10 a.m.-3 p.m. at American Jewish University's Brandeis-Bardin Campus, 1101 Peppertree Lane, Simi Valley. $50. For more information or to register, call (310) 440-1246.