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  • X-Matches Question

    I have a new female ?cousin relation? that just popped up. She is 60 years old and I am 44 years old. She has no idea of who her father is. She shares 297cM and the longest segment we share is 97cM. My mother has 508cM shared and 98cM shared longest segment. Family Finder's Match tools say that both I and this new relation are X-Matches.

    Question 1:
    Is it true that I need to march right up the maternal line of my family tree, ie mother, grandmother, great grandmother, second great grandmother to find my MRCA?

    Question 2:
    Based upon my mothers shared cM of 508, is it reasonable to say that this new realtion is either my mothers first cousin once removed from my Great Grandmother or second cousin to me?

    The other possibility is that my mothers great grand aunt, but that is a stretch because of age.

    Gregory MacBeth b. 1973 297/97cM
    |_ Betty Bryant b. 1932 508/98cM
    |_ Myrtle Catherine Godsey 1913-2005
    |_Abbie L Neely 1887-1965
    |_Ruthie Mary Neely "Morrow" 1847 - 1918
    |_Margaret Peggy Flynn 1827 - 1866

    Any help is greatly appreciated with the two questions

  • #2
    Originally posted by USMC7312 View Post
    I have a new female ?cousin relation? that just popped up. She is 60 years old and I am 44 years old. She has no idea of who her father is. She shares 297cM and the longest segment we share is 97cM. My mother has 508cM shared and 98cM shared longest segment. Family Finder's Match tools say that both I and this new relation are X-Matches.
    Question 1:
    Is it true that I need to march right up the maternal line of my family tree, ie mother, grandmother, great grandmother, second great grandmother to find my MRCA?
    Not for a possible X match (the pattern you describe in Question 1 would be for your direct maternal line, used for mtDNA matches). For ancestors who could have contributed to your X chromosome, you would need to consider other ancestors besides your direct maternal line ancestors (see charts linked below).

    How long is the shared segment on the X between you and your match? Does the match also share on the X with your mother (she should, because as a male, you got your only X chromosome from her), and how long is it? If the shared X segment is large enough, it may be of use in finding your common ancestor. If it is less than 10cM, I'm not sure if it will be helpful.

    Have you seen the charts from Blaine Bettinger's blog, in his post "Unlocking the Genealogical Secrets of the X Chromosome"? You can download them, and use the top chart for yourself, the lower one for your mother. Fill in the ancestors in the blue and pink shaded areas. Those are the ancestors who could have contributed an X chromosome to their children. If you prefer a table format, Debbie Parker Wayne has her "X-DNA Inheritance Charts" for male and female in three formats: Microsoft word, Rich Text, and PDF.

    Question 2:
    Based upon my mothers shared cM of 508, is it reasonable to say that this new realtion is either my mothers first cousin once removed from my Great Grandmother or second cousin to me?
    Using the chart on ISOGG's "Autosomal DNA Statistics" page, the relationship possibilities for your mother and the match range from first cousins once removed, half first cousins, great-great-grandparent/great-great-grandchild, great-great-aunt/uncle, half great-aunt/uncle, and double second cousins.

    Blaine Bettinger has also recently updated his charts: "August 2017 Update to the Shared cM Project," and provides a link on that page to a .pdf file with a lot of information on relationship possibilities based on amounts shared.

    The unknown father of your match may be an important link. You and the match may have to put your heads together and see if her mother was in a location where one of your male ancestors was, at the same time as the match may have been conceived.

    Here are a couple of other informative links about X inheritance:
    Last edited by KATM; 22 September 2017, 05:16 PM.

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    • #3
      The longest segment is 97 cM for me and 98 cM for my mother.

      Thank you for the detailed response. I will have to take some time to digest all this.

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      • #4
        Originally posted by USMC7312 View Post
        The longest segment is 97 cM for me and 98 cM for my mother.

        Thank you for the detailed response. I will have to take some time to digest all this.
        KATM was asking you what is the longest segment shared on the X Chromosome. Go to the Chromosome Browser then compare to your match and hover your cursor over the largest orange segment on the X chromosome.

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        • #5
          Here is the odd thing. FTDNA says that Janette is an X-Match to my mother as I, but Chromosome browser shows nothing on the X Chromosome.

          See the attached files.

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          • #6
            Originally posted by USMC7312 View Post
            Here is the odd thing. FTDNA says that Janette is an X-Match to my mother as I, but Chromosome browser shows nothing on the X Chromosome.

            See the attached files.
            Ok then that means disregard the X chromosome as you are matching this person below 5 cM. If you lower the threshold to 3 cM or 1 cM you will see the segment but it is no matter the X chromosome isn't of any significance here.

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            • #7
              So no to answer your original question this person doesn't have to be from any particular line of your mother's. She can be from any branch of your mother's tree (either side) we wouldn't be able to narrow it down to a specific branch for you just know this person is closely related.

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              • #8
                When you look on Chromosome Browser - on you, looking at your mother and this new cousin -- and on your mother, looking at you and this new cousin --
                on both, does it look like most of the matching is in the same place?
                on both - that really long segment - does it appear to be the same (well, almost the same) for both you and the new cousin and your mother and the new cousin? Or is possibly even on different chromosomes for one of you vs the other?

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                • #9
                  There are different possibilities but most likely a first cousin once removed or 1/2 first cousin to your mom. Use the in common feature between your mother and this match to try to narrow down which branch by trying to see what male and/ or female ancestors this person shares with your mother.

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                  • #10
                    The segments are the same except my segment to my mother is approx 1 cM larger. I was using the Matrix tool to try to see which side of the family had more in common in conjunction with the matches and chromosome browser tools. Unfortunately, I was getting as many connections in the Matrix tool on my mothers paternal side as her maternal side by surname. The problem is that my family genealogy resembles more of a vine than tree, but then again we have resided in South East Kentucky/North West Tennessee since 1773, at least until my generation.

                    I have attached the Matrix tool results.
                    Attached Files

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