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  • X dna matches

    My wife has now got 245 X matches and my son has 25!!!!! My wife matches my son with 18,092 X SNPs and 195.93 cMs. So it is strange the big difference in the number of matches. Does anyone else have X results like this?

  • #2
    Originally posted by 1798 View Post
    My wife has now got 245 X matches and my son has 25!!!!! My wife matches my son with 18,092 X SNPs and 195.93 cMs. So it is strange the big difference in the number of matches. Does anyone else have X results like this?
    There must be flaws in the method used to calculate matches. My son got his X from his mother and he should have a lot of matches that his mother has due to the fact that he matches her on all the X SNPs that were tested.

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    • #3
      Originally posted by 1798 View Post
      There must be flaws in the method used to calculate matches. My son got his X from his mother and he should have a lot of matches that his mother has due to the fact that he matches her on all the X SNPs that were tested.
      Your wife has two X chromosomes, one from her father and one from her mother. Your wife only passed down one X chromosome to your son which could be a combination of both or in some cases most or all of one of her X's.

      Since its not possible to split each X from your wife she will match people on the X when one or both of her two X's at each position is a match to one or both X's for females or the one X for males at those positions where as your son's single X will have to match one or both X's for females and the one X for males.

      What this means is that females will have far more X matches than males. The majority of X matches for females will be female to female as there are more possible SNP's due to both having two X's. Followed by female to male which is most common for men (I am male and have only 4 X matches at FTNDA, all female). Male to Male matches are the most uncommon as each only has one X.

      Your son's results are consistent for a male as it would be expected he would have fewer matches compared to his mother.

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      • #4
        Originally posted by awheaton View Post
        Your wife has two X chromosomes, one from her father and one from her mother. Your wife only passed down one X chromosome to your son which could be a combination of both or in some cases most or all of one of her X's.

        Since its not possible to split each X from your wife she will match people on the X when one or both of her two X's at each position is a match to one or both X's for females or the one X for males at those positions where as your son's single X will have to match one or both X's for females and the one X for males.

        What this means is that females will have far more X matches than males. The majority of X matches for females will be female to female as there are more possible SNP's due to both having two X's. Followed by female to male which is most common for men (I am male and have only 4 X matches at FTNDA, all female). Male to Male matches are the most uncommon as each only has one X.

        Your son's results are consistent for a male as it would be expected he would have fewer matches compared to his mother.
        My wife matches my son in every SNP with a single allele and for a lot of the time with the two alleles. I have examined both. I don't expect him to have as many matches as his mother but there is something strange about these results.

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        • #5
          The results are not strange. They are normal for X-chromosomes.

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          • #6
            Originally posted by 1798 View Post
            My wife matches my son in every SNP with a single allele and for a lot of the time with the two alleles. I have examined both. I don't expect him to have as many matches as his mother but there is something strange about these results.
            Males only have one X value, FTDNA lists it as an homozygous value, but in reality it is only A, C, G, or T, not AA, CC, GG, TT. (yes a small percentage of males values are listed as heterozygous, but it is not possible as they only have 1 X)

            Try the following

            -In your wifes chromosome browser download "Download All Matches to Excel (CSV Format)"
            -sort by chromosome Largest to Smallest (this should place all X matches at top of list)
            -Either copy and paste X section to new spreadsheet or delete all of the rest of the chromosome 1 thru 22 sections.

            -In your sons chromosome browser download "Download All Matches to Excel (CSV Format)"
            -sort by chromosome Largest to Smallest (this should place all X matches at top of list)
            -Copy his X section and paste it just below your wifes X section.
            -Sort by Name.
            -Delete shared names.

            In your wifes remaining X matches, how many of the are above 5cm with 700snp or more?

            These along with share matches with son are probably the only valid X matches your wife has.(Matches son has that mother does not, also are most likely false matches on X, especially true if match matches both mother and son on the autosomal chromosome)

            The rest are just creating a false match due to your wife have 2 X's so it is picking one value from one X and another value from her other X, bouncing back and forth between the two Xs values.

            Women tend to have more false X matches due to this, especially when it is two female matches compared together.

            This (false matches) also applies to chromosomes 1 thru 22, but you don't notice the difference in numbers of matches between males and females because each have two of each of these chromosomes.
            Last edited by prairielad; 19th February 2015, 01:50 PM.

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            • #7
              here is one example on my sisters X

              she matches another females on her X as (my sister received Fathers full X)
              45812472 to 51090015, 6.82cM, 625 SNPs
              100037158 to 105608829, 2.93cM, 600 SNPs

              This match matches my Father on chromosomes 9
              Chr 9, 77965877 to 89034953, 23.69cM, 3195 SNPs

              She(match) does not match my Father on X

              This match does not match my mother at FTDNA and X one to one at Gedmatch comparing my mother and this match with setting threshold to 5cM and 500 SNPs the following segment (False) shows up
              X 53915022 to 67945799, 3.3cM, 511SNPs, which does not match my above sisters segments

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              • #8
                Originally posted by prairielad View Post
                Males only have one X value, FTDNA lists it as an homozygous value, but in reality it is only A, C, G, or T, not AA, CC, GG, TT. (yes a small percentage of males values are listed as heterozygous, but it is not possible as they only have 1 X)

                Try the following

                -In your wifes chromosome browser download "Download All Matches to Excel (CSV Format)"
                -sort by chromosome Largest to Smallest (this should place all X matches at top of list)
                -Either copy and paste X section to new spreadsheet or delete all of the rest of the chromosome 1 thru 22 sections.

                -In your sons chromosome browser download "Download All Matches to Excel (CSV Format)"
                -sort by chromosome Largest to Smallest (this should place all X matches at top of list)
                -Copy his X section and paste it just below your wifes X section.
                -Sort by Name.
                -Delete shared names.

                In your wifes remaining X matches, how many of the are above 5cm with 700snp or more?

                These along with share matches with son are probably the only valid X matches your wife has.(Matches son has that mother does not, also are most likely false matches on X, especially true if match matches both mother and son on the autosomal chromosome)

                The rest are just creating a false match due to your wife have 2 X's so it is picking one value from one X and another value from her other X, bouncing back and forth between the two Xs values.

                Women tend to have more false X matches due to this, especially when it is two female matches compared together.

                This (false matches) also applies to chromosomes 1 thru 22, but you don't notice the difference in numbers of matches between males and females because each have two of each of these chromosomes.
                @ prairielad,thanks a lot.

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                • #9
                  Originally posted by 1798 View Post
                  @ prairielad,thanks a lot.
                  When people wrote that a child got a recombined X from the mother, I forgot that the son only gets a single X and so a single allele. When I looked at the file it showed my sons SNPs AA,GG,TT and CC and it should be just A,G,T and C. His mother has a lot of SNPs that are AG,TC etc.



                  I have a FF match who has two sisters tested but I only match two of them.

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                  • #10
                    I forgot to mention that my Wife's X matches all match on other chromosomes above 8 cMs.

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                    • #11
                      I have 13 X-matches here at FTDNA. One X-match, that looks to connect to my mysterious direct maternal line, shows a plausible scenario. It seems to go back to an Ulster-Scots origin. Before that, either pure Scots (Argyle) or just a boring Anglo-Saxon, depending on which spouse it came from. But I have to study it a bit more.

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                      • #12
                        Originally posted by PDHOTLEN View Post
                        I have 13 X-matches here at FTDNA. One X-match, that looks to connect to my mysterious direct maternal line, shows a plausible scenario. It seems to go back to an Ulster-Scots origin. Before that, either pure Scots (Argyle) or just a boring Anglo-Saxon, depending on which spouse it came from. But I have to study it a bit more.
                        I recently revised my direct maternal line, switching to a different brother in the Wheeldon family. This gives me a different wife, unfortunately at a brick wall. Anyway, her line could end up coming from England, or in one possible case from Perthshire, Scotland. Her maiden name was Lee, and there are zillions of Lee lines out there.

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