Tuesday, September 19, 2017

Endogamy, A Closer Look (Part 3)

This is the third post in a series examining 355 pairs of my own relatives who have tested, looking at how much DNA each shares in total as well as the size of the largest segment.  (The previous posts in the series can be seen here and here.)

Everyone here has 100% Ashkenazic Jewish ancestry unless noted otherwise in the "Comments" column.  All numbers are as given by GedMatch with the exception of comparisons with Benjamin, JudithB, Shannon & Layla who are only on FamilyTreeDNA.

For each relationship section, I give the expected amount of shared centimorgans according to ISOGG.  I've also added in low/high ranges (at the 99th percentile) and average amounts shared according to the Shared Centimorgan Project (SCP) based on feedback to the first post.  In addition to looking at overall shared DNA for each pair, I also note the size of the longest shared segment.  Each relationship section gives the average amount of shared DNA and largest segment looking at those who have 100% Ashkenazic Jewish ancestry.


This post discusses people who have tested and who are known third cousins and more distant.  It also discusses some of those who are known to be related to one another in more than one way.  For those double cousins, I added the expected amounts of shared DNA for the two relationships for the ISOGG values.  I also added together the two low values, high values and average amounts given for the two relationships by the SCP.
Endogamy gives you lots of matches.  What does a true match look like?

Third Cousins (53.13cM expected ISOGG; 0-217/74 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Howard / Ed61.315.4Howard 1/2 AJ
Howard / My mother00Howard 1/2 AJ
Ron / Ed141.230.6
Ron / Scott96.327.7
Ron / My mother97.217.8
Karen / Howard69.931.2Howard 1/2 AJ
PatS / Howard105.726.6Howard 1/2 AJ
Sara / Ed173.726.1
Sara / My mother56.719.3
Sara / Leslie24.28.9
Sara / Sandy71.828.4Sandy 3/4 AJ
Sara / Karen103.721.1
Dave / Me298.560.3Dave 1/4 AJ
Liz / Me103.618.9Liz 1/4 AJ
Mark / Me108.830.4Mark 3/4 AJ
Marve / Ed98.827.5
Marve / My mother9727.2
Marve / Howard86.531.9Howard 1/2 AJ
Marve / Karen27.49.7
Marve / PatS153.737.8
Debra / Me225.481.1Debra 1/4 AJ
PattyBG / Me264.962.4Patty BG 1/4 AJ
Elise / Sid140.445.5
Elise / My father121.627.2
Elise / Susie91.431.9
Average (for 100% AJ) 101.66cM 25.59cM

Third Cousins Once Removed (26.56 expected ISOGG; 0-173/48 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Howard / Me8.88.8Howard 1/2 AJ
Ron / Me7117.8
Sara / Me81.913.6
Mark / Sandy165.433.9Mark & Sandy 3/4 AJ
Mark / Sara75.936.6Mark 3/4 AJ
Marve / Me94.523.7
Elise / Me142.427.2
Shannon / Me7218Shannon 1/8 AJ
Average (for 100% AJ) 97.45cM 20.58cM

Fourth Cousins Twice Removed (3.32 expected / 0-109/22)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Avishay / Ruth102.431.2
Average (for 100% AJ) 102.4cM 31.2cM

Fifth Cousins Once Removed (1.66 expected ISOGG; 0-79/21 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Avishay / Ed102.428.1
Avishay / Scott21.714.7
Avishay / My mother129.527.8
Avishay / Ron74.521.9
Average (for 100% AJ) 82.03cM 23.13cM

Sixth Cousins (0.83 expected ISOGG; 0-86/21 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Avishay / Me109.528
Average (for 100% AJ) 109.5cM 28cM

Double Second Cousins Once Removed (212.5 expected ISOGG; 0-632/246 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
JudithB / Ruth44659
Esther / Ruth20844.5
Average (for 100% AJ) 327cM 51.75cM

Double Second Cousins Twice Removed (106.25 expected ISOGG; 0-522/148 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Jonathan / Ruth285.744.5
Average (for 100% AJ) 285.7cM 44.5cM

Double Second Cousins Three Times Removed (53.13 expected; 0-278/114 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Layla / Ruth12613
Average (for 100% AJ) 126cM 13cM

Double Third Cousins (106.25 expected ISOGG; 0-434/148 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
JudithB / Ed14320
JudithB / Scott29435
JudithB / My mother22129
JudithB / JudithK29649
JudithB / Leon19732
JudithB / Fern25137
JudithB / Jerry21032
Esther / Ed85.919
Esther / Scott167.349.2
Esther / My mother185.529.6
Esther / JudithK138.421.8
Esther / Leon87.917.7
Esther / Fern69.916.5
Esther / Jerry167.628.7
Average (for 100% AJ) 179.61cM 29.75cM

Double Third Cousins Once Removed (53.13 expected ISOGG; 0-346/96 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Jonathan / Ed4720.8
Jonathan / Scott142.827.8
Jonathan / My mother156.728.2
Jonathan / JudithK175.727.9
Jonathan / Leon111.122.1
Jonathan / Fern14939
Jerry / Jonathan92.222
JudithB / Me19329
Esther / Me168.428.5
Average (for 100% AJ) 137.32cM 27.26cM

Double Third Cousins Twice Removed (26.56 expected ISOGG; 0-232/70 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Layla / Ed00
Layla / Scott17331
Layla / My mother11329
Layla / JudithK15629
Layla / Leon13023
Layla / Fern13738
Layla / Jerry15723
Average (for 100% AJ) 123.71cM 24.71cM

Double Fourth Cousins (26.56 expected ISOGG; 0-254/70 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Jonathan / Me117.527.8
Average (for 100% AJ) 117.5cM 27.8cM

Double Fourth Cousins Once Removed (13.28 expected ISOGG; 0-234/56 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Layla / Me14630
Average (for 100% AJ) 146cM 30cM

Second Cousin Once Removed & Third Cousin Once Removed (132.81 expected ISOGG; 0-489/211 ISOGG)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Ben / Ed168.624.1
Ben / My mother10220.2
Karen / Ben123.329.9
PatS / Ben79.617.7
Average (for 100% AJ) 118.375cM 22.98cM

Third Cousin & Fourth Cousin (66.41 expected ISOGG; 0-344/109 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Ben / Me51.713.8
Average (for 100% AJ) 51.7cM 13.8cM

Third Cousin Once Removed & Fourth Cousin Once Removed (33.2 expected ISOGG; 0-290/76 SCP)

Pair of relatives Total cM shared (GedMatch) Longest segment in cM Comments
Ben / Howard53.319.4Howard 1/2 AJ
Average (for 100% AJ) n/a n/a


The next post in this series will talk about conclusions that I am making from this data.  So stay tuned for more!

Note:  I'm on Twitter.  Follow me (@larasgenealogy).

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11 comments:

  1. AmySeptember 19, 2017 at 11:02 PM

    Wow, those are some wild AJ averages. It helps to explain all those false second to third and second to fourth cousins we (AJ test takers) all get as matches. Isn't the next question---how do we know when a match is really even somewhat as close as the testing companies estimate? Is this all just a waste of time and money for most AJ test takers if we can't tell a second cousin from a fifth cousin twice removed? I will await your conclusions.

    ReplyDelete
    Replies
    1. Lara DiamondSeptember 20, 2017 at 11:25 AM

      There are still some strategies to figure out which matches are worth investigating. It isn't a waste of time and money though. While the predictions may be off, you can use these strategies to identify which matches have a higher probability of being real 3rd cousins rather than much much more distant.

      Delete
    2. AmySeptember 20, 2017 at 12:00 PM

      I am not sure what those strategies are, but alas, for me, it has been pretty much a waste of time and money. I have found it only useful to confirm relationships I've discovered through traditional research. It's been useless as a tool to find new connections or to answer the two basic questions I had when I sent for my first of ten tests several years ago.

      Delete
    3. Lara DiamondSeptember 20, 2017 at 12:18 PM

      How about this? https://larasgenealogy.blogspot.com/2017/09/endogamy-closer-look-part-3.html

      Delete
    4. AmySeptember 20, 2017 at 12:29 PM

      Isn't that a link to this blog post?

      Delete
    5. Lara DiamondSeptember 20, 2017 at 12:38 PM

      Whoops, try this one: <a href="https://larasgenealogy.blogspot.com/2017/03/a-technique-for-endogamous-dna-using.html>https://larasgenealogy.blogspot.com/2017/03/a-technique-for-endogamous-dna-using.html</a>

      Delete
    6. AmySeptember 20, 2017 at 2:35 PM

      Thanks---I will give it a try---after the holiday! Right now I am trying to cook two kugels at once! Shana tova, Lara!

      Delete
    7. Lara DiamondSeptember 20, 2017 at 5:26 PM

      Shana tova!

      Delete
  2. ChuckSeptember 20, 2017 at 2:25 PM

    Laura, thank you for all the work you have out into this project.

    ReplyDelete
  3. AmySeptember 20, 2017 at 2:41 PM

    Ah, yes---largest segment. Yeah, I've tried that also. I had one person with whom my mother shared a segment of over 30 cM (and only about 85 overall cM). We could not find one thing in common in our ancestry. Thanks!

    ReplyDelete
  4. YoellieDecember 15, 2017 at 1:01 PM

    Great info! Thanks for doing this. My surprise half 2nd cousin and I share a whopping 390cM. He is half Jewish and I am 100%. BUT.... on my maternal side , the side we match on, my grandparents are 1st cousins. Another surprise for me was a known 3C1R with whom I share only 48cM over 8 segments. This one has me taking a closer look at my seemingly endogamous matches.

    ReplyDelete

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