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Thread: You're sure of Jewish ancestors, yet you got a low score with the Jtest? (<1%)

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    You're sure of Jewish ancestors, yet you got a low score with the Jtest? (<1%)

    Are there any DNA enthusiasts here that are bumping into the same situation? Knowing to have Jewish ancestors +- 5/7 generations ago, but scoring 1% or less with the Jtest? Yet matching to tons of Jews in the one-to-many section? Share your story! I could use all the info for my project.

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    i get 4.44 or something like that for Ashkenazi on the Jtest but I am part Italian and have 20 or so Italian name matches on my GEDmatch list. there are some names that sound Jewish as well.

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     Sergi (09-14-2017)

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    Quote Originally Posted by Sergi View Post
    Are there any DNA enthusiasts here that are bumping into the same situation? Knowing to have Jewish ancestors +- 5/7 generations ago, but scoring 1% or less with the Jtest? Yet matching to tons of Jews in the one-to-many section? Share your story! I could use all the info for my project.
    The opposite for me, I get 4,9% Ashkenazi on Jtest, my Y-HG has a good chance of being Jewish, yet I don“t match many Jews on Gedmatch Genesis and no Jewish family history at all.
    You could check your matches Jtest score. Relying on surnames often turned out to be a false positive.
    For example, with Bergman, Kohn and Rubin surnames scoring below 3% Ashkenazi.
    Last edited by Nive1526; 09-14-2017 at 12:40 AM.

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    Quote Originally Posted by Nive1526 View Post
    The opposite for me, I get 4,9% Ashkenazi on Jtest, my Y-HG has a good chance of being Jewish, yet I don“t match many Jews on Gedmatch Genesis and no Jewish family history at all.
    You could check your matches Jtest score. Relying on surnames often turned out to be a false positive.
    For example, with Bergman, Kohn and Rubin surnames scoring below 3% Ashkenazi.
    Already went through that. I match with 92 fully Jewish persons (and with fully Jewish persons I mean Jews with no non-Jewish ancestors, at least no recent ones), that score 23 up to 39% Ashkenazi on the Jtest.
    Last edited by Sergi; 09-14-2017 at 12:59 AM.

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    Quote Originally Posted by Sergi View Post
    Already went through that. I match with 92 fully Jewish persons (and with fully Jewish persons I mean Jews with no non-Jewish ancestors, at least no recent ones), that score 23 up to 39% Ashkenazi on the Jtest.
    Jtest is imperfect as Jews are not from Mars or other race, but a mixture of Levantines, south-Euros and North euros. But due to the fact that they suffered a great bottleneck, there a lot of jewish-specific genes, and Ashkenazi component is based on it. Average Jew would score about 27% Ashkenazi as far as i remember, but persons with no Jewish ancestry will show some percentage of this component increasing in direction of Mediterraian and Levant.

    So all in all it's only usefull for people with more than 10% of Ashkenazi ancestry.

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    Quote Originally Posted by Roaring View Post
    Jtest is imperfect as Jews are not from Mars or other race, but a mixture of Levantines, south-Euros and North euros. But due to the fact that they suffered a great bottleneck, there a lot of jewish-specific genes, and Ashkenazi component is based on it. Average Jew would score about 27% Ashkenazi as far as i remember, but persons with no Jewish ancestry will show some percentage of this component increasing in direction of Mediterraian and Levant.

    So all in all it's only usefull for people with more than 10% of Ashkenazi ancestry.

    some of the mixed mode population groups (two group Oracles) I get that magical 10% or so.... but since the Jtest is suppose to be "the test" so far, I am just under half of that.

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    Only works Ashkenazi and it works very well for them actually though, the oracle does a good job at differentiating real admixture from just random variation. From the runs I've done on Ashkenazis kits it is very accurate as long as you are atleast 25% Ashkenazi. I know this because was trying to search for non-Ashkenazi kits in my half-Jewish friend's matches using Jtest to test and it was always very accurate at >25% but occasionally it would work at 12.5%. But it also depends on what you are mixed with if you are like part Italian or something its going to hard time deciphering the difference.
    But honestly if you match closely with a ton of Jewish kit you're probably Jewish, its very easy to tell if someone is Jewish just looking at their matches because of Jewish endogamy.

    (BTW when I am taking about % Ashkenazi I'm referring to actual heritage not the Ashkenazi component on Jtest.)

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    Quote Originally Posted by Sergi View Post
    Are there any DNA enthusiasts here that are bumping into the same situation? Knowing to have Jewish ancestors +- 5/7 generations ago, but scoring 1% or less with the Jtest? Yet matching to tons of Jews in the one-to-many section? Share your story! I could use all the info for my project.
    Please remember that you can inherite nothing from 5/7 generations ancestors. Nothing specific here.

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     AJL (09-20-2017)

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    Quote Originally Posted by Saba123 View Post
    Only works Ashkenazi and it works very well for them actually though, the oracle does a good job at differentiating real admixture from just random variation. From the runs I've done on Ashkenazis kits it is very accurate as long as you are atleast 25% Ashkenazi. I know this because was trying to search for non-Ashkenazi kits in my half-Jewish friend's matches using Jtest to test and it was always very accurate at >25% but occasionally it would work at 12.5%. But it also depends on what you are mixed with if you are like part Italian or something its going to hard time deciphering the difference.
    But honestly if you match closely with a ton of Jewish kit you're probably Jewish, its very easy to tell if someone is Jewish just looking at their matches because of Jewish endogamy.

    (BTW when I am taking about % Ashkenazi I'm referring to actual heritage not the Ashkenazi component on Jtest.)
    It's not really the question whether I have Jewish ancestry or not. Just trying to learn what this Jtest really means and how accurate it is. But your answer was very interesting and helpful, thanks!

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    Quote Originally Posted by ffoucart View Post
    Please remember that you can inherite nothing from 5/7 generations ancestors. Nothing specific here.
    Are you sure? I got 3,2% middle-eastern DNA in my estimate, and the only ancestors it can originate from are the Jewish ones. Further there's no other ancestor in my tree that could be from the middle-east. I think I disagree, since MH explained to me that every percentage you inherit is, at the most, divided by two in every next generation. Like this:

    100% >>> 50%>>> 25%>>> 12,5%>>> 6,25%>>> 3,12%>>> 1,5%>>> 0,78%.

    I can imagine that below 0,78% it's not detectable anymore. But from 100% to 0,78% spans 8 generations, so I think you're wrong with stating that you cannot inherit anything from your ancestors from 5/7 generations ago
    Last edited by Sergi; 09-14-2017 at 12:57 PM.

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