Page 2 of 2 FirstFirst 12
Results 11 to 13 of 13

Thread: 23andme Matches

  1. #11
    Registered Users
    Posts
    177
    Sex
    Location
    Colorado, USA
    Ethnicity
    White European
    Nationality
    USA
    Y-DNA
    I-M223
    mtDNA
    T2b

    England Scotland Germany Switzerland Italy Norway
    Quote Originally Posted by maydonez View Post
    I share 2.14% of my DNA with my 3rd cousin(23andme predicted 2nd or 3rd but since we know each other, we fixed it to 3rd). You can see it in the image I uploaded.
    total shared DNA is 160 cM over 9 segments, biggest single segment is on 7th chromosome and 50cM.
    I don't know how come %0.89 can also be a 3rd cousin?
    I understand that shared DNA may vary(as provided by the cM Project) but the difference between 2.14% and 0.89% is really huge in my opinion.

    Attachment 22076
    It really does vary that much. 160 cM/2.14% is a little high for a 3rd cousin - according to DNA Detective's theoretical chart, it's out of range. But according to Bettinger's real world data, it is within range: 3rd cousins share an average of 74 cM, and a range of 0 cM - 217 cM so both amounts are well within the range of possibility. According to DNA Detectives, 10% of 3rd cousins won't share any DNA (or won't share enough to meet the min thresholds of an identical by descent match).

    This is the DNA Detective's chart: https://i0.wp.com/thednageek.com/wp-...tics-Chart.png

    And as I mentioned before, this is Bettinger's tool: https://dnapainter.com/tools/sharedcm

  2. The Following 3 Users Say Thank You to RobinBMc For This Useful Post:

     JFWinstone (03-12-2018), JMcB (03-13-2018), kw5368 (03-12-2018)

  3. #12
    Registered Users
    Posts
    770
    Sex
    Location
    Pittsburgh, PA, USA
    Ethnicity
    German-British-Catalan
    Nationality
    (U.S.) American
    Y-DNA
    R-YP619*
    mtDNA
    H1bg

    United Kingdom Germany Bayern Catalonia France Ireland Switzerland
    RobinBMc is quite right about how much variation there can be in shared % or shared cM even for the same relationship. Not only is this demonstrated by both DNA Detectives and The Shared cM Project, I can see it on the first page of my matches at Ancestry.

    I have four known 1st cousins once removed in my match list. All four are great grandsons of my paternal grandparents. Two are brothers; the third is their 1st cousin; and the fourth is a 2nd cousin to the other three.

    The two brothers shared the most DNA with me: 633 centimorgans shared across 31 DNA segments for one, and 590 centimorgans shared across 28 DNA segments for the other. Using DNA Detectives' chart (see RobinBMc's post #11 above), both of these actually share enough DNA with me to be possible 1st cousins instead of the 1st cousins once removed that they are.

    The other two cousins share 491 centimorgans shared across 26 DNA segments and 379 centimorgans shared across 25 DNA segments. This puts them solidly within the 1st cousin once removed group at DNA Detectives, and nowhere else -- although half 1st cousin and half great-aunt/uncle/niece/nephew are other possibilities in the same group. Note also that in The Shared cM Project, these last two cousins could belong to the 2nd cousin group.

    The point is, this represents a fairly wide variation in sharing in the same fairly close relationship. The last of these four cousins only shares about 60% as much DNA with me as the first of the four.
    Last edited by geebee; 03-13-2018 at 04:03 PM.
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & prob. Cherokee. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    FTDNA shows my hg as R-YP619*.

    GB

  4. The Following User Says Thank You to geebee For This Useful Post:

     JMcB (03-13-2018)

  5. #13
    Registered Users
    Posts
    770
    Sex
    Location
    Pittsburgh, PA, USA
    Ethnicity
    German-British-Catalan
    Nationality
    (U.S.) American
    Y-DNA
    R-YP619*
    mtDNA
    H1bg

    United Kingdom Germany Bayern Catalonia France Ireland Switzerland
    I could also make the same point -- about variation in DNA shared by different relatives of the same degree -- using 23andMe.

    All five of my full siblings have tested there, as well as my daughter and the two offspring of one of my brothers. Let's look at their sharing with their uncles and aunts:

    My daughter:

    highest sharing is 2100 cM in 43 segments (28.2%)
    lowest sharing is 1861 cM in 48 segments (25.0%)

    My niece:

    highest sharing is 2113 cM in 51 segments (28.4%)
    lowest sharing is 1819 cM in 49 segments (24.4%)

    My nephew:

    highest sharing is 1927 cM in 48 segments (25.9%)
    lowest sharing is 1720 cM in 44 segments (24.4%)

    This represents fifteen different aunt/uncle-niece/nephew relationships, with a range of sharing from a low of 1720 cM (24.4%) to a high of 2113 cM (28.4%). If I had test results for my other seven nieces and nephews -- which would give us an additional thirty-five aunt/uncle-niece/nephew relationships -- I'm sure the variation would be even greater.

    Now, if you had hundreds or even thousands of such relationships to consider, you might not be surprised to see that the range of sharing for this relationship at The Shared cM project is 1349 – 2175 cM. (The average is 1750 cM.)

    EDIT: I initially failed to account for two of my nieces and nephews!

    Actually, I have seen how much I share with my youngest niece: 2,026 centimorgans shared across 69 DNA segments. But she tested at a different company, and results between two companies may not be fully comparable.

    In addition, Ancestry uses an algorithm designed to eliminate matches they consider to be false -- but in the process a lot of real matching is also eliminated. As an example, Ancestry says that my v2 self matches my v1 self for 3,489 centimorgans shared across 25 DNA segments. Ancestry also says that my daughter and I have 3,468 centimorgans shared across 54 DNA segments.

    I guarantee that I should match myself 100%, so therefore it should be 23 DNA segments and not 25. I should also have exactly 23 segments (in the form of complete chromosomes) with my daughter, and not 54.
    Last edited by geebee; 03-13-2018 at 06:30 PM. Reason: Correction of miscount of nieces and nephews
    Besides British-German-Catalan, ancestry includes smaller amounts of French, Irish, Swiss, Choctaw & prob. Cherokee. Avatar picture is: my father, his father, & his father's father; baby is my eldest brother.

    FTDNA shows my hg as R-YP619*.

    GB

  6. The Following User Says Thank You to geebee For This Useful Post:

     JMcB (03-13-2018)

Page 2 of 2 FirstFirst 12

Similar Threads

  1. secondry ydna matches in 23andme
    By vettor in forum 23andMe
    Replies: 0
    Last Post: 09-04-2015, 09:01 PM
  2. My annoyance with 23andMe matches
    By BalkanKiwi in forum 23andMe
    Replies: 5
    Last Post: 08-16-2015, 07:47 PM
  3. Your surname matches on 23andme?
    By Piquerobi in forum 23andMe
    Replies: 2
    Last Post: 04-05-2015, 03:12 AM
  4. Interesting 23andme matches.
    By Roaring in forum Autosomal (auDNA)
    Replies: 3
    Last Post: 01-04-2015, 06:47 PM
  5. Y-dna Survey of your 23andme matches
    By MitchellSince1893 in forum R1b-P312
    Replies: 3
    Last Post: 09-23-2014, 05:06 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •