RJ Magazine Top Menu

Cracking the Code" Discussion and Study Guide


Spring 2008 cover

The Associated Press (1/12/08) reported, "About 3.5 million of today's Jews…are descended from just four women, a genetic study indicates…Together, their four signatures appear in about 40 percent of Ashkenazi Jews, while being virtually absent in non-Jews and found only rarely in Jews of non-Ashkenazi origin…."

Jon Entine explores this and other astounding findings. He considers how genetic anthropology and genetic signatures comprise an amazing scientific tool to trace ancestry, assess health risks, and – in a more controversial vein – alter genetic makeup itself.

So far, genetic detective work among Jews reveals:

  • The majority of Jewish males shares a Middle East ancestry that dates back 4,000 years.
  • Only about 50% of Jewish females are genetically linked to the Middle East; the others appear to be descended from gentiles.
  • Some 30% of the Ashkenazi gene pool has genetic markers from a variety of local, non-Jewish populations among which Jews lived.
  • Most Jewish men claiming to be kohanim (of priestly descent) carry markers that originated about 3,000 years ago.
  • The African Lemba tribe carries Jewish markers, including a 53% frequency of kohanim markers among the tribe's priests, supporting the tribe's claim of Israelite descent.
  • Markers among Asia's Indian Jews suggest that they descended from biblical Israelites.
  • Despite their tradition of Solomonic descent, Ethiopian Jews carry no Jewish marker.
  • Many Southwestern conversos and Hispanos descend from Sephardim on the male side.
  • One in four Ashkenazi Jews carries genetic risk for diseases like Tay-Sachs, Familial Dysautonomia, and Cystic Fibrosis.
  • Some forms of breast cancer are found only in Jews and their descendents.

Genetic mapping, combined with anthropology and history, illuminates the Jewish record. Ashkenazi and Sephardi Jews, for example, became separate populations because of differing experiences in differing locations, starting with the exile at the time of the Babylonian destruction of the First Temple (6th century BCE). Genetic mapping is also a disease-fighting weapon to screen prospective parents for gene-related illness. In-marrying (endogamous) groups, such as Orthodox Jews, are more likely than out-marrying (exogamous) groups to carry such genes. Genetic screening helps reduce the frequency of passing these genes to succeeding generations. For example, over the last decade, screening decreased the incidence of Tay-Sachs in the U.S. by 90%.


In "Cracking the Code," Entine raises perplexing, challenging questions: What's the significance of human differences? How – or should – genetic knowledge influence human behavior, especially one as basic as selecting a marriage partner? And more.

These discussions appear under "THREE BIG IDEAS":

A. Genetic anthropology provides a new way of looking at Jewish identity.

B. Genetic advances shed new light on Jewish history.

C. Genetic mapping raises difficult ethical questions.

NOTE: Space precludes the discussion of Ashkenazi and Sephardi history and culture. For this, refer to earlier Reform Judaism magazine articles and discussion/study guides, and the selected sources listed at the conclusion of this guide.

A. Genetic anthropology provides a new way of looking at Jewish identity.

1. Kinship marriage puts Jewish populations at genetic risk. Therefore, says Entine, "the best of all possible worlds is for Jews to marry non-Jews who convert to Judaism."

a. Should Jews be encouraged to marry non-Jews who convert to Judaism? Why/why not?

b. Would you advise your children to do this? Explain.

c. How does this idea relate to the Union for Reform Judaism's Outreach program, a primary discussion in Reform Judaism magazine, Winter 2007? (See resources below.)

2. "Genealogy is the second most popular American hobby after gardening…a national obsession." Yet, "family trees are typically investigating events from the past few centuries…Most of us have a sense of our family history, but eventually we hit a brick wall. Our DNA breaks through that wall…leads from the present into the realm of deep ancestry." –Wells, p. 11ff.

Jewish genealogy is a rewarding family activity, supported by many Internet resources such aswww.pitt.edu and www.jewishgen.org. (See David, below, for helpful hints for the novice genealogist.)

a. Speak to your relatives to identify and learn about extended family members: their dates of birth, marriage, and death; their countries of origin; their physical characteristics; their health patterns; and more. Construct a family tree to show the relationships. (The CD ROM program, Family Tree Maker, is a helpful tool for families interested in a more extensive tree project.)

b. What have you learned about generational physical characteristics? About health patterns?

c. How does your tree begin to answer the "ancestry" question, "Where did we come from?"

3. Entine observes that many of today's Ashkenazi Jewish women carry genes suggesting descent from gentiles; and, since we do not know whether these gentile women converted to Judaism, their female descendants may not be Jewish according to traditional Jewish law.

a. If this is indeed the case, is this positive or negative for Jewish survival? Explain.

b. How does the Reform Movement’s commitment to patrilineal descent (children raised as Jews by Jewish fathers and non-Jewish mothers are considered Jewish) play a role in answering the question, "Who is a Jew"? If this analysis is accurate, is patrilineal descent a better approach to Jewish identity than the traditional, matrilineal, descent? Explain.

4. Ethiopian Jewish refugees, known as Beta Israel, entered Israel under the Law of Return – as Jews – before genetic mapping was available. Now we know they carry no Jewish markers. However, the historical evidence indicates that many Ethiopians steadfastly adhered to Jewish beliefs and practices starting some 2,500 years ago, when their ancestors appear to have converted to a Judaism. Their tradition attaches their origin to Jerusalem Jews who accompanied Menelik (the presumed son of King Solomon and the Queen of Sheba) back to his country. Other theories suggest that Judaism reached them through Jews living in Saudi Arabia, Egypt, or Ethiopia.

a. Should Israel continue to regard the Ethiopian Jews as Jews? Explain.

b. Are genetic markers an irreducible necessity to being a Jew? Explain.

B. Genetic advances shed new light on Jewish history.

1. Gene mapping shows that our biblical ancestors comprised a single population only after King Solomon's time (about 950 BCE), contradicting the biblical Abraham-Sarah, Isaac-Rebecca, Jacob-Leah/Rachel narratives placed about a thousand years earlier.

a. Does this information affect our identity as a Jewish People? Explain.

b. How would you interpret the earlier biblical material in the light of the genetic finding?

c. Discuss the meaning of "biblical ancestor" with your children. (See # A. 2, above.)

2. Most Jewish men claiming to be kohanim--of priestly descent--carry genetic markers that originated about 3,000 years ago, at the time of Moses and Aaron (the first High Priest).

a. What is the importance of this genetic fact? Does it "prove" that Aaron existed? Explain.

b. Is it important for your Jewish identity to know whether Aaron – or, for that matter, Moses – ever existed? Explain.

c. Many Jews still identify as Kohanim, Levites, and Israelites. What do you think about dividing Jews into these classes, or castes?

3. Jewish gene mapping is a sub class of a science publicly lauded on June 26, 2000 at the White House: "The first complete sequence of the human genome – the 2.85 billion units that make up our genes…As Clinton said, 'the most important, most wondrous map ever produced by humankind.'" –Wells, p. 1-2. More recently (1/18/08), the New York Times reported that millions of people are buying commercial saliva-testing kits to learn whether they are at risk for genetically produced disease that medical intervention might prevent. A federal panel and doctors have warned against using the kits because manufacturers' claims for their efficacy "are unproved, ambiguous, false or misleading."

a. How can we best assess the relative promises and pitfalls of new discoveries?

b. Would you seek out reliable medical gene testing for possible disease risk? Why/why not? If yes, what questions would you wish to have answered?

c. Has Jewish gene mapping had an impact on your family? If so, how?

C. Genetic mapping raises serious ethical questions.

1. Entine forecasts that in the future, all humans will carry a card showing the major genetic influences that produced them. Chapman, p. xi, notes, "Rapid breakthroughs in genetic research…advances in molecular biology, and new reproductive methods have advanced our understanding of how we might approach genetic interventions as possible remedies for diseases caused by genetic disorders…."

a. What are the pros and cons of the technologies Entine (and Chapman) are suggesting? Would you want to carry a "gene map" card? What if it might help in getting you medical intervention to head off disease?

b. The Associated Press (January '08) reported the discovery that a combination of five gene variants raises the risk of prostate cancer. The research might even lead to a blood test to detect men at risk. If so, should testing be mandatory? Who decides? Who pays for the screening? Who gets the information?

c. Should you tell members of your extended family about genetic diseases you might be carrying? Explain.

d. Is it necessary, or wise, always to act on the knowledge and procedures provided by expanding frontiers in these sciences? Explain.

2. Entine warns that gene-testing can be misused. History records horrendous consequences. In their zeal to produce a “master race,” the Nazis applied the so-called science of eugenics (meaning "good birth," coined by Francis Galton, c.1850) to eliminate "inferior" individuals and groups. For many decades, American institutions sterilized the "unfit" in their care.

a. Should doctors tell prospective parents that an in-utero embryo will develop a debilitating or deadly disease? Explain.

b. In vitro fertilization enables prospective parents to select the "best" from among several embryos they produce. Is this a good or bad idea? Explain.

c. In their quest to produce embryos free of inherited disease, British scientists have created a single human embryo from two women and a man (USA Today, 2/6/08). What social policy questions does this procedure prompt? Does it require control? What sort? By whom? Explain.

3. "There has always been a fear of scientists delving into mysteries.…Copernicus feared it enough to delay publication…until just before his death. Galileo discovered what happens when a scientist ignores the fears and dogma of his time…And then there are the truly evil scientists, the most chilling example being the Nazi doctor and scientist Josef Mengele.…Faust's bargain still articulates…that the day may come when we go too far in peeling back the unknowns…" –Duncan, p. 144

a. Have geneticists gone too far? How do you feel about genetically modified foods, for example?

b. Should government have the authority to control genetic research? Explain.

c. The F.D.A. recently approved cloned meat products for human consumption. Do you agree with the decision? What do your children think? Discuss.

4. "…This man (Craig Venter, human genome co discoverer)...is actually setting out to create new life forms…that will function according to his instructions…such as eating up CO2 pollutants in power plants or producing hydrogen for fuel cells." –Duncan, p. 138

a. Should we allow the search for new life forms? Why? Why not?

b. If yes, whom would you authorize to guard against unintended consequences? Explain.

c. What questions should an ethical review panel ask about such research?

5. "We (Duncan and James Watson) talked about genetic engineering–tinkering with the double helix he co-discovered–and I asked whether he worries about a genetic divide: that people with access to genetic fixes and enhancements will become a new subspecies, or species.” –Duncan, pp 176-177

a. Who should have access to a new gene that cancels mental illness, or prolongs life?

b. If discovered, should we require everybody to receive an HIV-resistant gene? Explain.

c. Who should make these kinds of decisions? Explain.


A. General

1. Alan D. Bennett. "Outreach: The Next Generation" - Discussion and Study Guide.

2. Audrey R. Chapman & Mark S. Frankel. Designing Our Descendents: The Promises and Perils of Modern Genetics. Baltimore: Johns Hopkins Univ. Press. 2003.

3. Jo David. How to Trace Your Jewish Roots. NY: Citadel Press. 2000.

4. David Ewing Duncan. The Geneticist Who Played Hoops with My DNA. NY: William Morrow. 2005.

5. Spencer Wells. Deep Ancestry: Inside the Genographic Project. Wash. DC: National Geographic. 2006.

B. Sephardim

1. Marc. D. Angel. La America: The Sephardic Experience in the United States . Philadelphia: JPS.1982.

2. Martin Gilbert, Ed. The Illustrated Atlas of Jewish Civilization. Macmillan: New York. 1990. Text and maps of Jewish settlements from Abraham to the 20th century.

3. Lucien Gubbay & Abraham Levy. The Sephardim . London: Carnell. 1992.

4. Devorah & Menachem Hacohen. One People: The Story of the Eastern Jews: Twenty Centuries of Jewish Life in North Africa, Asia and Southeastern Europe . New York: Sabra/Funk & Wagnalls. 1969.

5. Reform Judaism magazine articles and study guides.

6. www.sephardim.com

C. Ashkenazim

1. Ruth Ellen Gruber. Upon the Doorposts of Thy House: Jewish Life in East-Central Europe Yesterday and Today. NY: J Wiley. 1944.

2. Paul Kriwacazek. Yiddish Civilisation: The Rise and Fall of a Forgotten Nation. NY: Alfred A. Knopf. 2005.

3. Milton Meltzer. A History of Jewish Life from Eastern Europe to America. Northvale NJ: Jason Aronson. 1996.

4. Diane K. Roskies & David G. Roskies. The Shtetl Book. NY: KTAV. 1975, 1979.

5. Mark Zborowski & Elizabeth Herzog. Life is With People: The Culture of the Shtetl. NY: Schocken. 1952.

6. Jewish Life in the Middle Ages (video). West Orange NJ: Behrman House. 1993.