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  • #16
    Great job, Biblioteque! And TexasYaYa, congratulations on finding a (half) sister!

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    • #17
      Just a word of caution, full X match between two females (which share total cM range as half siblings) does not 100% mean you share a father.
      It is the most likely scenario but not fact.
      Two females can be maternal half sisters, aunt/niece or paternal Grandmother to Granddaughter (age will definitely rule out Grandparent to Grandchild)

      Aunt to niece can be in the same age range, so age can not rule out relationship without further research.

      I will give a few examples of this:
      My mother and her younger sister are the same age as their nieces and nephews, children of their older siblings (oldest sister was born in 1929, my mother and sister born late 40's, all full siblings)
      My sister and my maternal aunt share along the full length of X, due to how recombination happened when my sister inherited random mixture of our mothers maternal X (same segment that is shared with aunt) and our mother paternal X (aunt and mother have identical paternal X from father)

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      • #18
        Biblioteque and TexasYaYa, did the GEDmatch One-to-One Comparison show any Fully Identical Regions on other chromosomes, besides the X?
        • From Kitty Cooper's blog, an example of how half siblings match (NO FIRs)
        • An example from ISOGG's "Fully Identical Regions" page, showing how double first cousins match/ (green areas showing matching FIRs) "The fully identical regions are shown in green, half-identical regions are shown in yellow, and non-matching regions are shown in red. The large blue blocks indicate matching segments of 7 cMs or more."
        Both the above examples are from GEDmatch comparisons, as shown in the linked articles in my first post of this thread.

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        • #19
          prarielad, thank you for sharing the variables, thednageek, Leah Larkin, wrote in her May 19, 2019, blog in the comments section, "At Gedmatch do a one-to-one comparison. Sisters who share a father should match across the entire X Chromo." And, yes, she said "should", and not "would." Leah has a phD in biology and does work for MIT, et al.

          My paternal aunt and I do not share across the entire length of the X. But, we do share 63.96 cMs on the X.

          What do you suggest the OP (original poster) do as the next step to try to 100% confirm that her match is her half sister?

          And, yes, lest we forget, DNA is random and variable. And thank you again for putting a finer point on this.
          Last edited by Biblioteque; 21st September 2019, 10:04 AM.

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          • #20
            KATM, Total Half Matches (HIR) = 1959.9 cM (54.650 Pct) and 60.797 Pct SNPs are fully identical.

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            • #21
              prairielad, if the most likely relationship is either half sibling or double first cousin (per Shared DNA Project and DNA Detective statistics), and the two possibilities given by TexasYaYa are that her match could be either the child of her brother or her aunt, then do you think based on the One-to-One comparison at GEDmatch (1959.9 cM half-identical), it shows they are half siblings?

              Although it's also a possible relationship, TexasYaYa has eliminated the possibility of niece/nephew. From what information has been provided so far, it seems that there are no siblings for either the father of TexasYaYa, or her match at Ancestry. TexasYaYa seems to have one sibling, a brother who was too young to be the Ancestry match's father. We haven't seen that any other matches for TexasYaYa and her Ancestry match show up as aunts/uncles or niece/nephew.

              It seems to me that the only way they could be half siblings is via TexasYaYa's father, because if the match was the child of TexasYaYa's aunt, they would be first cousins, and the amount of shared DNA would be less. And, double first cousins would share sizable Fully Identical Regions, which apparently isn't the case here. You've said that it's possible that TexasYaYa and her Ancestry match could be maternal half sisters, vs. paternal via TexasYaYa's father. Couldn't TexasYaYa clear this up by viewing the Ancestry match's shared matches with her? If TexasYaYa can identify any of the shared matches at either Ancestry or GEDmatch as either paternal or maternal, wouldn't that answer that question?

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              • #22
                KATM, thank you for further analyzing this. So the ball is in TexasYaYa's court, and we will hope to hear from her.

                Also, hope Dr. Ann Turner will opine.
                Last edited by Biblioteque; 21st September 2019, 12:24 PM.

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                • #23
                  I misstated the part about siblings ("there are no siblings for either the father of TexasYaYa, or her match at Ancestry"). I should have said that from what we know, Texas YaYa's father has a sister, and TexasYaYa has a brother, but the match (as far as is known) does not have a sibling. Although the amount of shared DNA could be shared by a niece/nephew (or even a grand-niece/nephew), it doesn't seem that the Ancestry match is a niece from the known sibling information given.

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                  • #24
                    I know it has to be on the paternal side because she had no matches with my mother. She can’t be my niece because my brother was 8 years old. I have confirmed she can’t be an aunt because my grandmothers were both in their 60’s and had both had hysterectomies in their 40’s. Therefore a half sibling had to be the only option. As far as the other questions about matches, I don’t understand enough how to use gedmatch to be able to answer.

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                    • #25
                      Originally posted by TexasYaYa View Post
                      I know it has to be on the paternal side because she had no matches with my mother.
                      Were there shared matches to any people you could definitely identify as on your father's side? This would give positive evidence that the match is paternal, rather than by eliminating a maternal relationship and assuming a paternal one.

                      Do you have some maternal relatives who have tested at Ancestry, OR uploaded to GEDmatch? Or perhaps none of your maternal relatives have done any DNA testing for genealogy/ethnicity. Are you sure that there is no possibility that your mother could have had a child within 5 years of having you, and gave her up? I'm just considering all possibilities, to eliminate some of them.

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                      • #26
                        Originally posted by KATM View Post

                        Were there shared matches to any people you could definitely identify as on your father's side? This would give positive evidence that the match is paternal, rather than by eliminating a maternal relationship and assuming a paternal one.

                        Do you have some maternal relatives who have tested at Ancestry, OR uploaded to GEDmatch? Or perhaps none of your maternal relatives have done any DNA testing for genealogy/ethnicity. Are you sure that there is no possibility that your mother could have had a child within 5 years of having you, and gave her up? I'm just considering all possibilities, to eliminate some of them.
                        My mom didn’t have another child because she had an emergency hysterectomy when I was born. I do have a lot of maternal relatives and she didn’t match with any of them, but we do have shared 200ish 3,4 etc cousins.

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                        • #27
                          Originally posted by prairielad View Post
                          I will give a few examples of this:
                          My mother and her younger sister are the same age as their nieces and nephews, children of their older siblings (oldest sister was born in 1929, my mother and sister born late 40's, all full siblings)
                          My sister and my maternal aunt share along the full length of X, due to how recombination happened when my sister inherited random mixture of our mothers maternal X (same segment that is shared with aunt) and our mother paternal X (aunt and mother have identical paternal X from father)
                          To be sure I understand, you are saying that your mother and her sister both inherited their father's X, which is not recombined, and then your mother passed this same unrecombined paternal X chromosome to your sister, so that she matches her maternal aunt on the same full X (as well as her mother). It is a paternal X that has been passed down intact, which came from your mother's father to her and her sister (your maternal aunt), as the father got it from his mother.

                          I got a bit confused when you said "My sister and my maternal aunt share along the full length of X, due to how recombination happened when my sister inherited random mixture of our mothers maternal X (same segment that is shared with aunt)," since that does not seem likely to be "the full length of X" chromosome that your mother and aunt (and sister) all match completely. The rest of the sentence was clear.


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                          • #28
                            Originally posted by TexasYaYa View Post

                            My mom didn’t have another child because she had an emergency hysterectomy when I was born. I do have a lot of maternal relatives and she didn’t match with any of them, but we do have shared 200ish 3,4 etc cousins.
                            Okay, thank you for the further information. It sounds like the answer is that your father is the father of your Ancestry match, so she is your paternal half-sister, and the connection is solved.

                            Comment


                            • #29
                              https://dnapainter.com/tools/sharedcmv4

                              TexasYaYa, Your top 4 matches at GEDmatch in the 224-265cMs range after Tricia (half sister) seem to be from your mother's side because none of them in a one-to-one comparison match Tricia who is from your father's side. The 3 kits of Liz from my experience look to be her dna from 3 different testing companies, rather from dna from a bro/sis of hers.

                              The dna painter above will help you with relationships. This is a guide, without crossover/recombination factored in, so there are variables.

                              Do you know any of your top matches (3 kits of Liz and randolj1)?

                              I guess my post is gratuitous because I now see that KATM had already wrapped it up. Thank you, KATM.
                              Last edited by Biblioteque; 21st September 2019, 03:29 PM.

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                              • #30
                                Originally posted by Biblioteque View Post
                                https://dnapainter.com/tools/sharedcmv4

                                TexasYaYa, Your top 4 matches at GEDmatch in the 224-265cMs range after Tricia (half sister) seem to be from your mother's side because none of them in a one-to-one comparison match Tricia who is from your father's side. The 3 kits of Liz from my experience look to be her dna from 3 different testing companies, rather from dna from a bro/sis of hers.

                                The dna painter above will help you with relationships. This is a guide, without crossover/recombination factored in, so there are variables.

                                Do you know any of your top matches (3 kits of Liz and randolj1)?

                                I guess my post is gratuitous because I now see that KATM had already wrapped it up. Thank you, KATM.
                                I know that Liz is also adopted and that’s why she has had so much testing from different companies. Jody Randol is on my mothers side, also adopted. Are you saying they matched my “half sister” as well? If so now I’m really confused. However my maternal grandmother and grandfather were both adopted. My grandmother was given to a “sweat home” when she was 5 because her parents couldn’t afford all the kids. I feel like I’m in a “Flowers in the Attic” book right now.

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