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Understanding Centimorgans

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  • Understanding Centimorgans

    I am trying to find my Dad's missing grand father, my great grand father, and have a match on that is a "2nd Cousing" with 375 centimorgans across 19 segments. This person tree has 8 generations with no surnames in common with mine.

    According to the Shared CM Project chart that would make them 1st cousin 1 removed, 1st cousin 2 removed, 2nd cousin or 2nd cousin 1 removed.

    Am I reading that correctly and should I assume that our missing grand father is somewhere between the 1st and 4th generation on their tree?

    Other proven connections in my tree are:
    Close Family: 1756 cm
    1st cousin: 932 cm
    2nd cousin: 616 cm
    3rd cousin: 146 cm

    The person in question has not loaded their dna results into GedMatch or FamilyTreeDNA so I can't compare and have not answered a couple email requests.

    Is it reasonable to think that somewhere in their 1st 4 generations is my great grand father?

    Thanks for looking.


  • #2

    Jon, perhaps this will be helpful.


    • #3
      That's great that they have a tree!

      Make sure you screen shot the tree in case they decide to change access to it. I prefer to screenshot the tree in pedigree view. Do you have many mutual matches, and do they have trees?

      400cM is about average for a first cousin once removed or a half-first cousin.

      Who tested - yourself or your father?


      • #4
        Biblioteque: Thanks! great tool. I do so much better with a visual representation.

        ltd-jean-pull: Thanks for the advice to screen shot. I did that and also downloaded a list of all the name in their tree.

        Yes there are several shared matches but the names in the trees do not match. I have chased down every other line except this one and the surnames in their tree do not match any of the other line in mine.

        This person is 375cm to my dad and 167cm to me.

        Both my dad and I have autosomal tests through Ancestry. I have y37 DNA test, no help so far, and am waiting on my dad's y37 DNA results.


        • #5
          Does your dad have any siblings who will test?
          your father only received 50% of your grandfather, his siblings will carry some of the other 50% which may contain portions of DNA of your Great Grandfather that your father did not receive.

          On average testing 4 or more siblings will give close to complete coverage of missing parents DNA (85+%)


          • #6
            My dad is the last of his siblings.


            • #7
              Just got my dad's y37 results and nothing new.

              Super discouraged!