Interpreting DNA test that shows mother was 1/3 Jewish?


I'm assuming that my mother's mother was full or 2/3 Jewish for my mother to end up being 1/3 Jewish. So what does that make me (her son)? Would I be considered to be of Jewish decent if my mother is only part Jewish?


Posted 2016-07-28T00:25:05.620

Reputation: 11

5Please recognise that "Jewish" is a broad, ill-defined ethnicity that is (I would argue) in its modern form largely an American construct. Judaism is a religion. Certainly ethnic groups can be similar in distribution to religious groups but they are not the same thing. A DNA test cannot tell you if you are Jewish, but it may tell you that you are descended from certain Jewish populations. – Harry Vervet – 2016-07-28T00:56:35.530

3How can anyone be 1/3 anything? You are either fully X (if both parents were), or 1/2 X or not at all, or 3/4 (if one of your parents was fully X, the other 1/2 X), or 7/8, etc. The denominator is always a power of 2. – user3697176 – 2016-07-28T15:57:08.673



According to Jewish religious law, a person is Jewish if either their mother is Jewish, or if they convert to Judiasm.

If your mother is not 100% Jewish, then you need to know if her mother (your grandmother) was Jewish. If she was not 100% Jewish, then keep following the maternal line until you find a woman who was either fully Jewish or was not at all Jewish.

So your mother being 2/3 Jewish or 1/3 Jewish will not provide the answer. In fact, if all your 16 great-great-grandparents were Jewish except for your mother's mother's mother's mother, then you would not be Jewish even though your DNA would be 15/16 or 94% Jewish.

Note that conversion to Judiasm counts as 100% Jewish (noting that Reform and Conservative conversions are not always accepted by the Orthodox). Children born prior to the conversion are not Jewish, but children born after are. If one of your mother's line of ancestors converted to Judiasm, then you could be Jewish without any Jewish DNA. Similarly, conversions go the other way as well, and you could be non-Jewish with 100% Jewish DNA.

What this all means is that with regards to DNA and descendancy, you can match the average Jewish population to any percentage, but that neither makes you Jewish or non-Jewish.


Posted 2016-07-28T00:25:05.620

Reputation: 16 148


It says that your ancestors and most likely you share a certain number of genetic markers that are more common in populations that adopted Jewish belief somewhen over the last millennia. (This makes them closely related to other groups living in the Near East, e.g Palestinians, see e.g. Ostrer: The population genetics of the Jewish people. Hum Genet 2013). It is also likely that ancestors of your grandmother also practiced Judaism, a possible family background that is interesting and worth to be researched.

Providing percentages on "being Jewish" is not useful from a biological perspective and also problematic from a historical perspective (antisemitic classification by Nuremberg Laws like "3/4 Jewish", although not based on genetics but on ancestry).


Posted 2016-07-28T00:25:05.620

Reputation: 5 041