As the series Finding Your Roots with Henry Louis Gates, Jr. begins its 10-week run on PBS, The Spittoon will feature posts from 23andMe’s Ancestry Ambassadors featuring their own stories about using DNA to dig into ancestry.
By Tim Janzen, M.D.
My father, Robert Janzen, comes from a long line of hardworking Low German Mennonite farmers. But when 23andMe developed the feature to identify Ashkenazi Jewish heritage, I really wanted to determine whether his data suggested any Jewish ancestry. Let me explain.
His Mennonite ancestors were persecuted in the Low Countries — in what is now the Netherlands and Belgium — and in the 1500s they fled to a safer haven in what is now Poland. After Catherine the Great opened Russia to settlers, his ancestors migrated to South Russia between 1789 and 1819 where they established small villages of Mennonites on the Russian Steppe. After many hardships they eventually prospered and developed thriving agricultural colonies that helped transform South Russia into the “breadbasket” of the world before about a third of the Mennonites immigrated to the United States in the 1870s.
The Mennonites who lived in Poland and Russia were an endogamous religious group, meaning they rarely married others who were not adherents to their faith. But there were many exceptions to that practice, and over the centuries a significant number of non-Mennonites joined the Mennonite faith. Relatives on my father’s mother’s side have said that one of our ancestors was Jewish. My father’s great uncle Johann Peters conveyed that we descend from a Catholic priest who married a “redheaded Jewess” sometime in the distant past. Who this was we do not know. According to the historical record between 1750 and 1790 26,000 Jewish followers of Jacob Frank converted to Christianity in Poland. Perhaps my Jewish ancestor was among them.
Traditional genealogical tools and family stories helped to identify some possibilities. There was Joseph Nowitzky (1776-1844), whose ancestry is cloaked in mystery. The Nowitzky name is found among Ashkenazi Jews, and family stories from relatives in Canada said that Joseph Nowitzky was a traveling Jewish salesman whose daughter Maria Nowitzky lived with a Mennonite family and eventually married a son from that family. But written records from South Russia suggest that Joseph Nowitzky had become a Mennonite by 1801. He and his family are listed in the major Mennonite censuses from 1801 to 1816. Another relative has heard that we are descended from a woman of Jewish background named Justina von Liechtenstein.
So I was faced with a problem many genealogists confront — an end to the paper trail and conflicting family stories. This is where using DNA can help. While any two people’s genomes are 99.5 percent identical, that small bit of difference is incredibly important. It’s what makes each of us unique and it allows genetic genealogists to find relatives and map out information about our ancestry.
Fundamentally this comes down to making comparisons, either between individuals to see how closely they are related, or comparing an individual to groups of individuals to determine common ancestry. The closer two people are related, the more similar their DNA. The more shared ancestry a person has with a group, the more segments of DNA he or she shares with that group of people.
23andMe compares individuals in their database with its Relative Finder tool and finds potential matches. Using an advanced tool called “Ancestry Finder,” you combine Relative Finder matches with ancestry survey information about the country of origin of their grandparents. This can help tell you more about your ancestry. You can also tweak the controls and increase or decrease the length of the matching segments, measured in a unit called centimorgans (cMs).
When I set the minimum segment size to five cMs, set the number of grandparents from the same country to one and clicked the box to show Ashkenazi Jewish ancestry, Ancestry Finder indicated that between 2 percent and 3.8 percent of my father’s DNA is of Ashkenazi Jewish origin. Results for my father’s sisters are similar and the average amount of DNA that is of Ashkenazi Jewish origin for my father and his four sisters is 2.27 percent.
I also have data from two distant relatives who descend from my father’s great-great-grandparents, Jacob Peters (b. 1823) and Helena Bergmann (b. 1826). Helena Bergmann’s mother was Justina Nowitzky, who was a daughter of Joseph Nowitzky. The Ancestry Finder results indicate that my father’s relatives have an average of 4.35% Ashkenazi Jewish ancestry. This would be consistent with each of them being approximately 1/32 Ashkenazi Jewish in origin. The Ancestry Finder results for my father and his sisters would suggest that they are about 1/64 Ashkenazi Jewish in origin.
I reviewed the 23andMe results of 33 other Mennonites, as well as the data from my father’s paternal cousins to see if they show any evidence of Ashkenazi Jewish ancestry. None of them show more than 1 percent Ashkenazi Jewish ancestry. These results confirm that my father indeed has Ashkenazi Jewish ancestry on his mother’s side. I cannot prove at this time that the Ashkenazi Jewish ancestry came through Joseph Nowitzky, but that is a strong possibility. If the Jewish ancestry wasn’t from Joseph Nowitzky then it could have come from one or more of Jacob Peters’ and Helena Bergmann’s great-grandparents.
In any case the Ancestry Finder results from 23andMe confirm that my father does have Jewish ancestry as related in the family stories told by his great uncle Johann Peters. Whether that ancestor was truly a redheaded Jewish woman may never be determined, but the 23andMe Ancestry Finder results certainly provide fascinating confirmation of an interesting family legend!
Tim Janzen is a family practice doctor at South Tabor Family Physicians in Portland, Oregon. His interest in genealogical research goes back 35 years and he has particularly focused on Mennonite genealogy for the past 15 years. He has a web site that summarizes many different sources available for Mennonite genealogical research found at www.timjanzen.com and has given many presentations about Mennonite genealogy in the United States and Canada. He is the co-administrator of the Mennonite DNA project at www.mennonitedna.com. He also serves on the ISOGG Y-DNA Haplogroup Tree Committee. Tim is married to Rachel Janzen and they have four children.