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Jewish Ancestry Frequently Asked Questions

What are the challenges of Jewish genealogy?

Jewish genealogy includes many challenges that mean more frequent and problematic roadblocks for the Jewish genealogist than for the non-Jewish genealogist. The following are some of these challenges:

  • Surnames that pass from father to son were not adopted until the late 1700s and early 1800s.
  • Unrelated paternal lines have adopted the same surnames.
  • Related paternal lines have adopted different surnames.
  • Surnames have been adapted to the country where descendants live today.
  • In many cases, traditional paper trail records are lacking.
  • The Jewish population is endogamous (intermarrying).

Do I have Jewish ancestry on my direct paternal (Y-chromosome DNA) line?

Judaism is a religion and not an attribute definable by a DNA mutation, but we can give you hints about having Jewish ancestry by comparing your results against our database. Look on the Y-DNA – Ancestral Origins page to see whether or not the people you match have listed Jewish ancestry. Those in our Jewish database have a listing in the Comments column denoting Jewish ancestry. There are four situations when testing for Jewish ancestry. These situations are as follows:

  • You match only people who are also Jewish on their direct paternal line. That is, the signature or haplotype only matches with people who have known Jewish ancestry. The answer in this case is clear.
  • Your haplotype matches both Jewish and non-Jewish lineages. The answer is not clear, and we cannot guess whether or not your personal lineage is Jewish.
  • You match no one of known Jewish origin. The answer is clear. You are unlikely to have Jewish origins in this lineage.
  • You have no matches in our system at all. That means we have never seen your specific results. We will know more about your ancestry when you start matching others.

Do I have Jewish ancestry based on my Family Finder™ and myOrigins results?

Judaism is a religion and not an attribute definable by a DNA mutation, but we can give you hints about having Jewish ancestry by comparing your Family Finder results to those of known Jewish ancestry in our database. myOrigins results may also provide clues to recent Jewish ancestry in the last five generations.

The first clue to your having recent European Jewish ancestry is the number of matches you have in the Family Finder database. Due to endogamous marriage patterns, there is a high level of inter-relatedness in European Jews. If you have recent Jewish ancestry, you will then have a high number of Jewish cousins on your matches page, likely in the 1000s of matches.

The second clue to your having recent Jewish Ancestry comes from the myOrigins ethnic percentages results. Most people with Jewish genetic ancestry will see Ashkenazi or Sephardic Jewish ancestry here. However, if you show only a small amount of Jewish genetic matching, it is not proof of recent Jewish ancestry. This is because the genetic match may be from a much more distant genetic admixture that became fixed in your recent ancestors’ population. Please note that we are able to assist with Ashkenazi, Sephardic, Mizrahi, and Yemenite  Jewish ancestry at this time.

How do I tell if I have Jewish ancestry on my direct maternal (mitochondrial DNA) line?

Judaism is a religion and not a genetic attribute that can be defined by a DNA mutation. However, because Jewish populations have been endogamous for much of their history, hints to your Jewish ancestry for your direct maternal lineage are provided by looking at the mtDNA – Ancestral Origins page in your account. Check the Comments column on this page. There are four possible situations:

  1. You match only people who are Jewish. You will see in the Comments column Ashkenazim, Sephardim, and other historic branches. The answer here is a clear yes.
  2. You match both Jews and non-Jews. The answer here is not clear. A higher level of testing, the Mitochondrial DNA Full Genomic Sequence test, will eliminate matches with one group or the other.
  3. You match nobody of known Jewish origins. It is highly unlikely that you have Jewish origins on this line.
  4. You do not have matches in our system. This is unlikely if you have Jewish origins.

What percent of Jews carry the Cohanim Modal Haplotype (CMH)?

From surveys of markers in Jewish cemeteries, about 5% of Jewish men have historically been Cohanim. Genetic research indicates that many Jewish men who self-identify as Cohanim belong to the Y-chromosome DNA lineage that is most common in the Cohanim. That is, they belong to the Cohanim Modal Haplotype (CMH). Further, in a study conducted in Israel where men were asked at random if they were Cohanim, Levite, or Israel, of those answering Israel, about 3% when tested were part of the CMH lineage.

How does Y-DNA help with the challenges of Jewish Genealogy?

Unlike many other populations, the Jewish people adopted hereditary surnames relatively recently. Surnames changed during recent emigrations. Some families modified their surname spellings to fit with local norms. By testing the Y-chromosome DNA, you and your cousins can recover the linkage along a direct paternal line.

For example, someone has the surname Brown. They also have a family tradition that their ancestors and their cousins who moved to Australia and South Africa were Plikhs. By testing themselves and potential cousins with the Plikh surname, they can prove (or disprove) the family tradition.

How does the nature of Jewish genealogy make Y-DNA research more challenging?

Because Jewish genealogists cannot assume that paternal line ancestors have had the same surname for over 300 years, interpreting close and exact matches requires more thought and consideration than would otherwise be the case.

Where a non-Jewish genealogist with origins in a country such as England might see an exact Y-37 match with the same surname and use it to confirm a recent relationship,  Jewish genealogists must approach it more cautiously. They need to consider each family’s geographic origins and their knowledge of how the surname relates to their family history.

On the other hand, an exact Y-37, Y-67, or Y-111 match to someone with a different surname need not be a cause for alarm. Rather this is the potential discovery of a branch of the family that has undergone a name change.

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