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RE: [Ashkenazi-Q] Family/Relative Finder - False Positives for those with Ashkenazi ancestors

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  • Bob
    Dave, When I use the Advanced tab under labs/ancestry finder, https://www.23andme.com/you/labs/ancestry_finder/ I find that I am related too many declared
    Message 1 of 8 , Nov 22, 2010
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      Dave,

       

       When I use the “Advanced” tab under labs/ancestry finder, https://www.23andme.com/you/labs/ancestry_finder/

       

      I find that I am related too many “declared Ashkenazi Jews” & 7 – 8.3 % “not declared”, the totals of both covers just about every chromosome.  I think those matches come from way back in the 1700’s when my Scheib ancestors changes their name to Shipe here in America .  A Shipe was a footman for George Washington, so I like to think that my Jewish ancestors were trying to get even with oppression way back then.

       

       My point is your point that many Jews did choose to mix with others; however Ancestry Finder proves that the genetic mix lives on, even if diluted.  

       

      Bob Vick

      PS to maximize the hits, click the 1 in “# of grandparents from the same country”, and move the bar to 5cm matches, while clicking the Ashkenazi box.

       


      From: Ashkenazi-Q@yahoogroups.com [mailto:Ashkenazi-Q@yahoogroups.com] On Behalf Of Dave
      Sent: Sunday, November 21, 2010 6:48 PM
      To: Ashkenazi-Q@yahoogroups.com
      Subject: [Ashkenazi-Q] Family/Relative Finder - False Positives for those with Ashkenazi ancestors

       

       

      As I explained in my message discussing the Family and Relative Finder
      programs the theory is to look for long strings of identical DNA.

      Those of us with Ashkenazi Jewish ancestor have a problem. Our ancestors
      intermarried for centuries. Very little new DNA came into the group for
      hundreds and hundreds of years. In fact studies are showing that 60% of
      all our DNA goes back to the middle east. There may have been an
      infusion 1,200 years ago from the Khazars but most of the DNA pool has
      been recycled over and over again.

      Thus, if both your parents were of Ashkenazi descent they were probably
      cousins several times over. They may have been 4th and 5th cousins at
      the same time. Your grandparents were probably cousins several different
      ways.

      What this means is that all of us share some long strings of matching
      DNA that are just common to the group of us.

      The consequence of this is that we will get false positives from either
      the Family or Relative finder results. They will tell you that someone
      is your 3rd cousin when they are not even your 5th cousin. This will be
      just as maddening as having close yDNA matches and not being able to
      find the common ancestor.

      This all adds to the fun.

      I have some folks who match with me with long strings of DNA on 7
      different chromosomes with a prediction they are my 3rd cousins. We
      share no surnames or locations within many generations. A third cousin
      shares a great-great-grandparent.

      What really is happening is that the person they tell me is my 3rd
      cousin is really my 5th cousin three times or something similar.

      Enjoy,

      Dave

    • aj_levin
      After having tested four kits on 23andme, I have to say the false positives are a bigger issue there. 23andme has a cutoff of 1,500 relatives. This might be
      Message 2 of 8 , Nov 22, 2010
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        After having tested four kits on 23andme, I have to say the false positives are a bigger issue there.

        23andme has a cutoff of 1,500 "relatives." This might be okay, if not for the fact that the cutoff for smallest segment is set much too low. It is usually meaningless to genealogy if you share multiple 5.5, 6.0, possibly even 7.5 centimorgan segments with someone. Yes, you are related to them, but probably as many different ways as you have common segments, many or all of them likely from 1600 or earlier.

        Also, the algorithm seems to like total shared DNA rather more than longest block, which is usually a much better indicator of recent relatedness. And because the 23andme database is now at about 60,000, with about 6,000 Ashkenazi, and almost all Ashkenazim have enough shared DNA to be on each others' Relative Finder, the 1,500 limit is probably cutting off many legitimate matches and admitting many where there is no hope of a recent link.

        The Ashkenazi algorithm at 23andme creates a further problem if you are only partly Ashkenazi: it artificially doubles the predicted relatedness at the level of 3rd cousin and beyond for your non-Ashkenazi matches. And because, if the algorithm applies to you, you are called a "Distant Cousin" rather than "5th cousin" (even if you happen to be their 4th cousin), your invitations are less likely to be accepted, and others are less likely to initiate contact with you.

        Family Finder has a larger cutoff for smallest segment, which will reduce these older matches. They also have no cutoff in your number of matches, and a much higher response rate. They don't institute an algorithm, so some of the relationships are overstated; but on the other hand the Ashkenazi algorithm at 23andme still ends up in overstating many relationships. It is statistically impossible, for example, that my stepfather could have 35 third cousins and 100 fourth, all of whom happen to have tested at 23ande.

        Family Finder has a much smaller database but a much better response rate. You will probably have to initiate the contact to get anything out of it, but the same is true of 23andme, and with a better reply rate (for me about 90% as opposed to maybe 20% at 23andme) I find it rewarding, and 23andme frustrating.

        Best,

        A.J.


        --- In Ashkenazi-Q@yahoogroups.com, "Dave" <dshoward@...> wrote:
        >
        > As I explained in my message discussing the Family and Relative Finder
        > programs the theory is to look for long strings of identical DNA.
        >
        > Those of us with Ashkenazi Jewish ancestor have a problem. Our ancestors
        > intermarried for centuries. Very little new DNA came into the group for
        > hundreds and hundreds of years. In fact studies are showing that 60% of
        > all our DNA goes back to the middle east. There may have been an
        > infusion 1,200 years ago from the Khazars but most of the DNA pool has
        > been recycled over and over again.
        >
        > Thus, if both your parents were of Ashkenazi descent they were probably
        > cousins several times over. They may have been 4th and 5th cousins at
        > the same time. Your grandparents were probably cousins several different
        > ways.
        >
        > What this means is that all of us share some long strings of matching
        > DNA that are just common to the group of us.
        >
        > The consequence of this is that we will get false positives from either
        > the Family or Relative finder results. They will tell you that someone
        > is your 3rd cousin when they are not even your 5th cousin. This will be
        > just as maddening as having close yDNA matches and not being able to
        > find the common ancestor.
        >
        > This all adds to the fun.
        >
        > I have some folks who match with me with long strings of DNA on 7
        > different chromosomes with a prediction they are my 3rd cousins. We
        > share no surnames or locations within many generations. A third cousin
        > shares a great-great-grandparent.
        >
        > What really is happening is that the person they tell me is my 3rd
        > cousin is really my 5th cousin three times or something similar.
        >
        > Enjoy,
        >
        > Dave
        >
      • Dave
        Bob, Here are my results when I indicated that 2 of my grand parents were from the same country. My father was Ashkenazi Jewish. My mother is an American for
        Message 3 of 8 , Nov 22, 2010
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          Bob,

          Here are my results when I indicated that 2 of my grand parents were from the same country.

          My father was Ashkenazi Jewish. My mother is an American for generations back. She converted so she and my father could be married by a Rabbi.

          Click on This Link to See the 23andME results.
           
          Thanks for telling me about this report.

          Dave

          --- In Ashkenazi-Q@yahoogroups.com, "Bob" <Vick@...> wrote:
          >
          > Dave,
          >
          >
          >
          > When I use the "Advanced" tab under labs/ancestry finder,
          > https://www.23andme.com/you/labs/ancestry_finder/
          >
          >
          >
          > I find that I am related too many "declared Ashkenazi Jews" & 7 - 8.3 % "not
          > declared", the totals of both covers just about every chromosome. I think
          > those matches come from way back in the 1700's when my Scheib ancestors
          > changes their name to Shipe here in America. A Shipe was a footman for
          > George Washington, so I like to think that my Jewish ancestors were trying
          > to get even with oppression way back then.
          >
          >
          >
          > My point is your point that many Jews did choose to mix with others;
          > however Ancestry Finder proves that the genetic mix lives on, even if
          > diluted.
          >
          >
          >
          > Bob Vick
          >
          > PS to maximize the hits, click the 1 in "# of grandparents from the same
          > country", and move the bar to 5cm matches, while clicking the Ashkenazi box.
          >
          >
          >
          >
          > _____
          >
          > From: Ashkenazi-Q@yahoogroups.com [mailto:Ashkenazi-Q@yahoogroups.com] On
          > Behalf Of Dave
          > Sent: Sunday, November 21, 2010 6:48 PM
          > To: Ashkenazi-Q@yahoogroups.com
          > Subject: [Ashkenazi-Q] Family/Relative Finder - False Positives for those
          > with Ashkenazi ancestors
          >
          >
          >
          >
          >
          > As I explained in my message discussing the Family and Relative Finder
          > programs the theory is to look for long strings of identical DNA.
          >
          > Those of us with Ashkenazi Jewish ancestor have a problem. Our ancestors
          > intermarried for centuries. Very little new DNA came into the group for
          > hundreds and hundreds of years. In fact studies are showing that 60% of
          > all our DNA goes back to the middle east. There may have been an
          > infusion 1,200 years ago from the Khazars but most of the DNA pool has
          > been recycled over and over again.
          >
          > Thus, if both your parents were of Ashkenazi descent they were probably
          > cousins several times over. They may have been 4th and 5th cousins at
          > the same time. Your grandparents were probably cousins several different
          > ways.
          >
          > What this means is that all of us share some long strings of matching
          > DNA that are just common to the group of us.
          >
          > The consequence of this is that we will get false positives from either
          > the Family or Relative finder results. They will tell you that someone
          > is your 3rd cousin when they are not even your 5th cousin. This will be
          > just as maddening as having close yDNA matches and not being able to
          > find the common ancestor.
          >
          > This all adds to the fun.
          >
          > I have some folks who match with me with long strings of DNA on 7
          > different chromosomes with a prediction they are my 3rd cousins. We
          > share no surnames or locations within many generations. A third cousin
          > shares a great-great-grandparent.
          >
          > What really is happening is that the person they tell me is my 3rd
          > cousin is really my 5th cousin three times or something similar.
          >
          > Enjoy,
          >
          > Dave
          >
        • Dave
          AJ, Thanks so much for this great information. Have you shared your comments with the 23andME people? They always seem to be asking for feedback. I note that
          Message 4 of 8 , Nov 22, 2010
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            AJ,

            Thanks so much for this great information.
            Have you shared your comments with the 23andME people?
            They always seem to be asking for feedback.

            I note that you and I share a 6 cM chunk on Chromosome 9.
            However, that is it.

            Here is something interesting. Rebekah Canada is my 7th cousin on my mother's side. She and I share no segments.

            Dave
          • Bob
            Dave, Your results are interesting with many more declared Ashkenazi s than mine below. Ancestry Color Percent of Bob Vick s Genome Covered Not declared
            Message 5 of 8 , Nov 23, 2010
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              Dave,

               

                Your results are interesting with many more declared Ashkenazi’s than mine below.

               

              Ancestry

              Color

              Percent of Bob Vick's Genome Covered

              Not declared Ashkenazi Jewish

               

              49.3%

              50.3%

              Declared Ashkenazi Jewish

               

              0.2%

              1.2%

               

               These results are at maximum, including US & Canadian Ancestors which brought up some X chromosome hits. When I use the 2 grandparents from the same country the hits fall way back, with mostly Polish Ashkenazi connections.  I only know of Czech blood in my paper trail lines.

               

               I guess the point above could be that 50% of my ancestors forgot where they came from, or likely never knew as their parents protected them from histories realities.

               

              Cheers, Bob

               

              PS My brother has 87% of the same DNA that line up the same way as mine only 56% of the time in segments. He matches people that I do not match, so it is possible to have no segment alignment with some distant cousins, which a sibling might match on.

               

               


              From: Ashkenazi-Q@yahoogroups.com [mailto: Ashkenazi-Q@yahoogroups.com ] On Behalf Of Dave
              Sent: Tuesday, November 23, 2010 12:01 AM
              To: Ashkenazi-Q@yahoogroups.com
              Subject: [Ashkenazi-Q] Dave Howard's Askenazi Jewish DNA - See Snapshot

               

               

              Bob,

              Here are my results when I indicated that 2 of my grand parents were from the same country.

              My father was Ashkenazi Jewish. My mother is an American for generations back. She converted so she and my father could be married by a Rabbi.

              Click on This Link to See the 23andME results.
               
              Thanks for telling me about this report.

              Dave

              --- In Ashkenazi-Q@yahoogroups.com , "Bob" <Vick@...> wrote:

              >
              > Dave,
              >
              >
              >
              > When I use the "Advanced" tab under labs/ancestry finder,
              > https://www.23andme.com/you/labs/ancestry_finder/
              >
              >
              >
              > I find that I am related too many "declared Ashkenazi Jews"
              & 7 - 8.3 % "not
              > declared", the totals of both covers just about every chromosome. I
              think
              > those matches come from way back in the 1700's when my Scheib ancestors
              > changes their name to Shipe here in
              w:st="on">America . A Shipe was a footman for
              > George Washington, so I like to think that my Jewish ancestors were trying
              > to get even with oppression way back then.
              >
              >
              >
              > My point is your point that many Jews did choose to mix with others;
              > however Ancestry Finder proves that the genetic mix lives on, even if
              > diluted.
              >
              >
              >
              > Bob Vick
              >
              > PS to maximize the hits, click the 1 in "# of grandparents from the
              same
              > country", and move the bar to 5cm matches, while clicking the
              Ashkenazi box.
              >
              >
              >
              >
              > _____
              >
              > From: Ashkenazi-Q@yahoogroups.com
              [mailto: Ashkenazi-Q@yahoogroups.com ] On
              > Behalf Of Dave
              > Sent: Sunday, November 21, 2010 6:48 PM
              > To: Ashkenazi-Q@yahoogroups.com
              > Subject: [Ashkenazi-Q] Family/Relative Finder - False Positives for those
              > with As hkenazi ancestors
              >
              >
              >
              >
              >
              > As I explained in my message discussing the Family and Relative Finder
              > programs the theory is to look for long strings of identical DNA.
              >
              > Those of us with Ashkenazi Jewish ancestor have a problem. Our ancestors
              > intermarried for centuries. Very little new DNA came into the group for
              > hundreds and hundreds of years. In fact studies are showing that 60% of
              > all our DNA goes back to the middle east. There may have been an
              > infusion 1,200 years ago from the Khazars but most of the DNA pool has
              > been recycled over and over again.
              >
              > Thus, if both your parents were of Ashkenazi descent they were probably
              > cousins several times over. They may have been 4th and 5th cousins at
              > the same time. Your grandparents were probably cousins several different
              > ways.
              >
              > What this means is that all of us share some l ong strings of matching
              > DNA that are just common to the group of us.
              >
              > The consequence of this is that we will get false positives from either
              > the Family or Relative finder results. They will tell you that someone
              > is your 3rd cousin when they are not even your 5th cousin. This will be
              > just as maddening as having close yDNA matches and not being able to
              > find the common ancestor.
              >
              > This all adds to the fun.
              >
              > I have some folks who match with me with long strings of DNA on 7
              > different chromosomes with a prediction they are my 3rd cousins. We
              > share no surnames or locations within many generations. A third cousin
              > shares a great-great-grandparent.
              >
              > What really is happening is that the person they tell me is my 3rd
              > cousin is really my 5th cousin three times or something similar.
              >
              > Enjoy,
              >
              > Dave
              >

            • aj_levin
              Hi Dave, They ve made an adjustment to Relative Finder, I think around September, that was a slight improvement. Some of us have voiced our concerns even after
              Message 6 of 8 , Nov 23, 2010
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                Hi Dave,

                They've made an adjustment to Relative Finder, I think around September, that was a slight improvement. Some of us have voiced our concerns even after that, but my impression is their resources go foremost to the medical side.

                As of today 23andme is doing away with the ancestry-only edition and only selling the complete edition; as a plus they've added people who had had the medical-only version to Relative Finder, and people who had ancestry-only should now be able to download their raw data to run through aftermarket progrmans such as Promethease. If you haven't logged in for a while you might also want to check for more close cousins.

                Our block on chromosome 9 (120,000,000-140,000,000) is not shared with either my paternal grandfather or my mother, so the link should be through my paternal grandmother, so probably an Ashkenazi but possibly a Sephardi link. At 6 cM we definitely share an ancestor, but it's going to be too far back to trace. So far I have only had sucecss with blocks about 9 cM and larger, and preferably at least 11 cM.

                As for your non-linking to Rebekah: I also have some 7th-9th cousins who I have shared genomes with and we have no common DNA showing.

                What happens is your autosomes are inherited in blocks from different ancestors, and while you inherit roughly half your DNA from each parent and roughly a quarter from each grandparent, just a couple of generations earlier you may have inherited many of your genes from one ancestor and none from another. Third cousins will almost always show up, but somewhere around 4th and 5th cousins, it starts to fall off.

                By seventh cousins, there's a fair chance one (and quite possibly both) of you inherited no genes from that ancestor -- or they've been chopped up in recombination, so they're there but not recognizable. That's why it's always good to test the oldest generation available.

                On the other hand if you have inherited _any_ genes from an ancestor beyond about five generations, they may also have been passed down intact with little recombiantion for many generations. That's why a fully Ashkenazi person might see a 5.5 or 6.0 cM block with someone from Spain, say, with converso ancestry, or from Italy; it really does go back 500-600 years to a common Sephardi or Italqi ancestor!

                I hope this helps...

                A.J.

                --- In Ashkenazi-Q@yahoogroups.com, "Dave" <dshoward@...> wrote:
                >
                > AJ,
                >
                > Thanks so much for this great information.
                > Have you shared your comments with the 23andME people?
                > They always seem to be asking for feedback.
                >
                > I note that you and I share a 6 cM chunk on Chromosome 9.
                > However, that is it.
                >
                > Here is something interesting. Rebekah Canada is my 7th cousin on my mother's side. She and I share no segments.
                >
                > Dave
                >
              • Dave
                Very interesting. That you and your brother are slightly different makes sense. Every sperm and every egg have slightly different mixes of the chromosomes.
                Message 7 of 8 , Nov 23, 2010
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                  Very interesting. That you and your brother are slightly different makes sense. Every sperm and every egg have slightly different mixes of the chromosomes.

                  --- In Ashkenazi-Q@yahoogroups.com, "Bob" <Vick@...> wrote:
                  >
                  > Dave,
                  >
                  >
                  >
                  > Your results are interesting with many more declared Ashkenazi's than mine
                  > below.
                  >
                  >
                  >
                  >
                  > Ancestry
                  >
                  > Color
                  >
                  > Percent of Bob Vick's Genome Covered
                  >
                  >
                  > Not declared Ashkenazi Jewish
                  >
                  >
                  >
                  > 49.3%
                  >
                  > -
                  >
                  > 50.3%
                  >
                  >
                  > Declared Ashkenazi Jewish
                  >
                  >
                  >
                  > 0.2%
                  >
                  > -
                  >
                  > 1.2%
                  >
                  >
                  >
                  > These results are at maximum, including US & Canadian Ancestors which
                  > brought up some X chromosome hits. When I use the 2 grandparents from the
                  > same country the hits fall way back, with mostly Polish Ashkenazi
                  > connections. I only know of Czech blood in my paper trail lines.
                  >
                  >
                  >
                  > I guess the point above could be that 50% of my ancestors forgot where they
                  > came from, or likely never knew as their parents protected them from
                  > histories realities.
                  >
                  >
                  >
                  > Cheers, Bob
                  >
                  >
                  >
                  > PS My brother has 87% of the same DNA that line up the same way as mine only
                  > 56% of the time in segments. He matches people that I do not match, so it is
                  > possible to have no segment alignment with some distant cousins, which a
                  > sibling might match on.
                  >
                  >
                  >
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