Sunday, June 26, 2011

DNA tests and genealogy

What does DNA testing tell a genealogist?
In search of my DNA genealogy

The Jewish Diaspora has been studied, rather exhaustively. DNA studies have added some important missing links to establishing a genealogical path.

What does DNA testing tell a genealogist? Without getting into the technicalities, the short answer to this question is that a person can learn about his/her biological ancestry from DNA tests. Through the Y-chromosome possessed only by males, one can correlate specific DNA characteristics with a growing collection of people throughout the world who are contributing their DNA for research. Women can ask fathers, brothers or male cousins to contribute DNA for their paternal side of the family.

I had long suspected that my paternal ancestors had followed one of the paths of Sephardic Jews, that is, Jews from Spain. Since they came from an Ashkenazic territory, proving this hunch was formidable, if not impossible. My paternal grandfather, Jonah Tucker, came from Dzenkiv, a shtetl near the larger settlement of Pogrebishche, a town near Kiev, where my grandmother, Chai Pessie Schakne, came from. When he arrived in Pittsburgh from Canada, he sought out a shul that used the Sephardic ritual (Nusach). This was a clue, but even my cousins thought such a choice meant nothing.

Along came that expanded the study of haplotypes and haplogroups (people with the same or very similar haplotypes). The large number of participants who submitted their own DNA gave researchers a greater ability to determine certain patterns of migration.

Current DNA studies indicate that while some Sephardim have attributes indicating ancestors from Palestine, a significant portion have attributes that indicate that they came from Western European stock. The deeper one goes into the Y-DNA, the closer one gets to a reliable answer to the question, “where did my paternal ancestor come from.”

Let me start with the broadest test called Y12. As I found out, it leads to a potential of false positives. I was told I fit into the haplogroup R1b. In reviewing the close matches, there was an overwhelming majority with non-Jews from Western Europe, particularly the British Isles, France and Switzerland.

I then requested a deeper study and went to Y-25, more than doubling the number of sites studied. The results came back. Again, my matches were predominantly from Western Europe. Only when I increased the study to Y-37 did I secure close matches with participants who (except for one) knew they came from Jewish backgrounds.

I sought out a better understanding of this coincidence from the founder and CEO of FamilyTreeDNA, Bennett Greenspan. In an email from him he said:

"It strongly appears that your male line is from R1b1a2a1a1b3 defined by the SNP (U-152) . . . derived, or downstream, from L23/L49, which is the ancestral SNP nearly exclusively found in the Middle East.

"I found some Jews in that Mediterranean database that is yet private from Turkey, Soviet Georgia and Morocco, and a Druze, but that dataset is inferior because it only uses our first 12 markers plus a few others (DYS 437/438), so I'm not satisfied with the resolution of the comparisons given your common overall signature in the genepool."

In other words, it looks like my paternal ancestor may have had roots in the Middle East, but only a more detailed study of the Y-DNA from participants who live in that area of the world might provide a definitive answer. I still cannot claim Sephardic roots.

One has to go fairly deep into the analysis of their Y-DNA to have anything close to an understanding of where their paternal ancestor came from. An example of not going far enough can be found in a monograph by Elizabeth Caldwell Hirschman and Donald Panther-Yates. They produce charts of men from New Mexico, who are descendants of early settlers from Spain. The predominant haplogroup is R1b. (“Toward a Sephardic Haplogroup Profile in the New World,” an unpublished monograph, available online through a service called SlideShare). Their conclusion is imprecise and misleading because the R1b haplotype is common in Western Europe and represents only the shallowest of study at level Y12. Recall that my results for 12 or even 25 markers matched with males from Western Europe. It was only when my study went out to 37 markers that matches were predominantly Jewish, but, even then, not necessarily Sephardic. I was fortunate to have Bennett Greenspan look more deeply into my haplotype (see quote above), but even then there was not enough evidence to make a convincing statement.

There is one group that has more of a chance to claim historic ancestry. The “Cohen” or “Kohanim” J-gene has apparent association with the patrilineal haplotype associated with Aaron, brother of Moses, and founder of the priestly dynasty of Judaism. A majority of present-day Kohanim either shares, or is only one step removed from a DNA string that represents possible descendants of Aaron. Not having a J-gene is more likely to disprove the claim of being a Cohen.

Haplotypes associated with Asian haplotypes occur infrequently among Jewish males but may indicate that their forefather was from Asia. Scandinavian haplotypes also occur as a result of incursions from the north into Russia. Blond and red hair color, while not a part of the Y chromosome, may be a tip off to a Scandinavian source of ancestry.

To this point I have only discussed male lineage. DNA tests are available for looking at mitochondrial (mtDNA) or DNA from our mother’s side. I had very close matches with nearly fifty others whose predecessors came from the same area of Eastern Europe of what my grandparents referred to as “White Russia” and what is now mostly Belarus. Many of the ancestors of Jews who lived there migrated from Italy. My great-grandmother’s maiden name, Resnick, is derived from what is now a suburb of Belgrade, a city that was once a sub-capital of the Roman Empire, and probably residence of many Jews.

Documentation is still the gold standard in establishing ancestral roots. For many of us who have Jewish roots, it is difficult to trace our heritage beyond the late eighteenth and early nineteenth century. I have documents and oral history that trace my ancestry back to 1830 in all but one case. As we go back in time, the number of our ancestors grows geometrically and surnames become more difficult because they were not fully established in Eastern Europe until the early nineteenth century. The genealogical road I have decided to take is to learn how my ancestors lived and migrated from place to place -- their story, and mine – a slice of Jewish history. DNA studies have placed a significant amount of guidance at my disposal.