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Need help- possible half-siblings also cousins

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  • Need help- possible half-siblings also cousins

    I uploaded my mother's Ancestry DNA data to FTDNA and got a female match 1652 cm, longest block 140, x match (89.34,96.8). Upon further research I have found this person's mother and my mom's mom were first cousins. I am searching for my mother's father. What else do I need to consider before I can place this female's father as my mom's father?
    I have researched cousin matches on Ancestry for about a year and with this information all the cousin cm amounts line up with that relationship.
    Any insight would be appreciated, let me know if additional clarification is needed.

  • #2
    Do they have any fully identical (green) segments on a one-to-one comparison?

    They match along the entire length of the X-chromosome?

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    • #3
      None show up as green. the x has one tiny break. What does this mean?

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      • #4
        Originally posted by janimann6 View Post
        None show up as green. the x has one tiny break. What does this mean?
        Can you post a screen shot? What is your total shared cM on X?
        Sister with same father will share their entire X with each other, due to fact father only has one which he passes on intact to all daughters, exception non matching may occur at the beginning or end of X which are the PAR regions where X and Y can recombine
        Paternal sisters will share around 194cM on X
        If you do, this is a strong indication that you will be paternal half sisters based on autosomal amount as well.

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        • #5
          Browser upload

          I attached a screen shot of chromosomes 7-x
          Chromosome 16 and 20 and the x (with the small break) are the most complete. The longest segment is 140 in chromosome 2, not shown.
          Attached Files

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          • #6
            Originally posted by janimann6 View Post
            I uploaded my mother's Ancestry DNA data to FTDNA and got a female match 1652 cm, longest block 140, x match (89.34,96.8). Upon further research I have found this person's mother and my mom's mom were first cousins. I am searching for my mother's father. What else do I need to consider before I can place this female's father as my mom's father?
            I have researched cousin matches on Ancestry for about a year and with this information all the cousin cm amounts line up with that relationship.
            Any insight would be appreciated, let me know if additional clarification is needed.
            Yes, please clarify. Are you saying you believe your mom is closely related on both sides of the family to your match? So this match is in theory a possible half sister to your mom (same father) through the match's paternal side while also being a known 2nd cousin on the match's mother's side? You should upload both your mom's and the match raw data to Gedmatch to see if there are any sizable green segments shared as this will indicate if your mom is possibly related on both sides to this match.

            Your mom and her match don't share much DNA to be both relationships unless they are sharing at the low end of half siblings. Maybe I am not understanding your post though as it is confusing.

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            • #7
              "So this match is in theory a possible half sister to your mom (same father) through the match's paternal side while also being a known 2nd cousin on the match's mother's side?"

              Yes, that is where I am trying to go with this. They share too much DNA to be only second cousins, I believe. I just discovered this match last week and the administrator for the test has not responded yet, so I am just trying to get clarity on what the potentiality is for this to lead to my mother's father's identity.
              Thank you all for continuing to look at this and respond.

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              • #8
                Originally posted by janimann6 View Post
                None show up as green. the x has one tiny break. What does this mean?
                Sorry - I didn't read your post correctly. You won't see any green segments at FamilyTreeDNA. The chromosome browser shows where you match, but not whether these segments are half-identical or fully identical.

                Did you also upload yours to Gedmatch?

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                • #9
                  My mother’s is uploaded to gedmatch but not her Ftdna match.

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                  • #10
                    Originally posted by janimann6 View Post
                    Yes, that is where I am trying to go with this. They share too much DNA to be only second cousins, I believe. I just discovered this match last week and the administrator for the test has not responded yet, so I am just trying to get clarity on what the potentiality is for this to lead to my mother's father's identity.
                    Thank you all for continuing to look at this and respond.
                    Thanks. So yes it could be possible but maybe a little lower DNA than what would be expected on average. But as mentioned FTDNA has no way of including the fully identical segments so the total reported DNA might be slightly less than what is actually shared. As mentioned see if your match would upload to gedmatch and then look at the segments in their chromosome browser to see if there are any nice sized green fully identical segments.

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                    • #11
                      Originally posted by janimann6 View Post
                      I uploaded my mother's Ancestry DNA data to FTDNA and got a female match 1652 cm, longest block 140, x match (89.34,96.8). Upon further research I have found this person's mother and my mom's mom were first cousins. I am searching for my mother's father. What else do I need to consider before I can place this female's father as my mom's father?
                      I have researched cousin matches on Ancestry for about a year and with this information all the cousin cm amounts line up with that relationship.
                      Any insight would be appreciated, let me know if additional clarification is needed.
                      Is the bolded above the total x matching segments? If so, mother and match are not half siblings (do not share father). It only adds up to 186cM, full share of x is 195cM roughly. 9-10cM gap is to large of a gap.

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