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  • Match on Family Finder full X

    I am male, my mum has just got a match and the X is the same as I have with my mum! 1370495 to 154570039, 195.93cM, 18092 SNPs

    There are no other major cM except a 8.48.

    Is this even possible or is it a glitch?






  • #2
    FTDNA don't take the X into account so place the match at 5th cousin. Here are the full chromosome amounts:

    1 44,805,958 47,629,198 1.44 600

    1 86,394,873 88,628,669 3.24 597

    3 163,183,135 168,639,652 2.74 800

    10 104,404,211 106,318,781 1.86 500

    11 13,382,409 16,194,663 2.88 700

    11 84,433,193 94,009,613 8.48 2,300

    12 6,939,881 9,852,782 4.03 700

    12 109,884,154 112,759,696 3.06 600

    16 64,798,732 67,158,356 2.65 500

    17 36,593,956 39,301,706 2.49 600

    18 39,563,514 41,490,428 2.39 500

    X 1,370,495 154,570,039 195.93 18,092

    Comment


    • #3
      As a male you only have one X chromosome, which you got entirely from your mother. So for you to match your mother 100% is normal.

      but for you to have a full X match with a distant match is very unusual. I know of one person who has watched an X match travel unbroken for four generations. Yours is probably greater.

      Comment


      • #4




        Thanks

        So do you think it is genuine and if so what range of cousin could this be?

        Originally posted by mabrams View Post
        As a male you only have one X chromosome, which you got entirely from your mother. So for you to match your mother 100% is normal.

        but for you to have a full X match with a distant match is very unusual. I know of one person who has watched an X match travel unbroken for four generations. Yours is probably greater.

        Comment


        • #5
          I would inquire with FTDNA to confirm, asking them to check this kits (match) Raw DAta to confirm it is a valid file (ie faulty transfer kit)

          Comment


          • #6
            Its very tough to predict the correct range of cousin, particularly after third or more, using the autosomes. The X is even worse, to the point that estimating relationships from the X is just unreliable. So the 8.3 suggests a fairly distant cousin, 4th to 5th according to the math. Slight chance of third. and 6th or 7th are also possible.

            I dont know what to make of the full X. I hope someone else chimes in. It does suggest closer rather than farther, but still hard to say.

            Does this person also match you on the X? Just pointing out you can match mum on one of her X chromosomes, and this person matches your mum on the other X, and so the person does not match you...

            It would be good if all three of you were also loaded at GedMatch so you can double check the X matching. Just to remove the glitch hypothesis you mentioned originally. I dont think it will make a difference, but I also believe in double checking everything when possible. There is also an X matrix tool at GedMatch.

            Comment


            • #7
              Thanks

              They don't match me on chr 1-22 so they don't show. So unfortunately I cannot compare with them alone.

              As you say I will suggest Gedmatch to them, however we are communicating via Google Translate as they are Spanish so Joining Gedmatch may be tricky


              Originally posted by mabrams View Post

              Does this person also match you on the X? Just pointing out you can match mum on one of her X chromosomes, and this person matches your mum on the other X, and so the person does not match you...

              Comment


              • #8
                I am awaiting their response on it

                Originally posted by prairielad View Post
                I would inquire with FTDNA to confirm, asking them to check this kits (match) Raw DAta to confirm it is a valid file (ie faulty transfer kit)

                Comment


                • #9
                  FTDNA reply:

                  "The issue appears to be with the matches' kit. The account has already been reported to our IT team and they are currently working to resolve the issue. Unfortunately we do not have a time frame for when this will be resolved, but I will add your information to their investigation. Thank you for your patience while we work to resolve this problem."



                  Apparently the transfer is from 23andMe and my mum is no match with them at any level.

                  So a major glitch needs to be rectified!

                  Comment


                  • #10
                    I just received an autosomal match 5th cousin to remote, with largest segment on C22, 8 cms but on the X C23 they match me the full length at 195 cm's . This just does not seem possible.

                    Comment


                    • #11
                      Quite unlikely, at best. And with such a weak autosomal match -- so weak, it may not even be real -- , there is essentially no way to pin down where the X match comes from, assuming it is real. I have to wonder from the two cases reported in this thread, if there might be a systemic problem at FTDNA, or else perhaps the two cases involve the same matching kit!

                      Comment


                      • #12
                        Makes me wonder if these kits are kits that are original 23andmeV5 kits modified.
                        I have read on various forums of people talking about how to convert to FTDNA accepted file.
                        But process inserts about 75% imputed values for the missing SNPs that FTDNA uses.
                        Most SNPs are usually one value or another, ie A or C, SNP will be AA, CC or AC,
                        Thus if majority of imputed SNPs are entered as the Heterozygous Allele (ie AC), they will match everyone.
                        It is the homozygous Alleles that create breaks in matching, ie) AC will match AA or CC, but AA will not match CC

                        would be curious if these files have a high Heterzygousity index. Higher the index the more likely to match others falsely.

                        Believe most people only have an heterzygousity index of around 25-30%
                        Attached Files
                        Last edited by prairielad; 16th November 2018, 06:47 PM.

                        Comment


                        • #13
                          Thanks prairielad. You wrote about something that I have been contemplating on for the past couple of days. So does GEDmatch on comparisons between two kits that both have AC on a particular SNP show a half match, full match, or no match? Does the same hold for the Family Finder, 23andMe, AncestryDNA, etc.?

                          Appreciate it.

                          Jack

                          Comment


                          • #14
                            Originally posted by georgian1950 View Post
                            Thanks prairielad. You wrote about something that I have been contemplating on for the past couple of days. So does GEDmatch on comparisons between two kits that both have AC on a particular SNP show a half match, full match, or no match? Does the same hold for the Family Finder, 23andMe, AncestryDNA, etc.?

                            Appreciate it.

                            Jack
                            If both show AC for a particular SNP it is shown as full base pair matching at Gedmatch (Green on Gedmatch one to one with Graphic)
                            the rest of the companies do not show full base pair matching as it really does not apply to most due to fact that it really only siblings that show significant blocks of Full base pair matching. Blocks is key, every one has SNPs that will show full base pair matching due to fact most SNPs can only be 1 or 3 Values, ie AA, CC or TT (or GG, TT, or GT), ect.

                            All matching algorithms are looking at your two letter value (ie AC) to a matches two letter value.
                            only one letter from each has to match
                            if only 1 of yours matches only one of matches it is a half match. ie) AC to AA, you match half base pair matching, or AC to CC, Matching only on ones maternal or paternal chromosome only
                            if both yours match matches two, then it is full base pair matching ie AC to AC , matching on both your maternal chromosome as well as your paternal chromosome
                            if both of you have different values completely, no match, ie AA to CC, not matching for that SNP on your maternal chromosome or your paternal Chromosome

                            Comment


                            • #15
                              prairielad, thanks again. I'd been taking SNP's between two sets of raw data and comparing them to the output of GM's chromosome browser using full resolution. Interestingly, full resolution not is full resolution in the sense that one pixel equals one SNP. GEDmatch obviously has some rules about how many adjacent full or half matches you have to have to show either on the image.

                              Of course, we do not have the means to assign a particular allele to a parent. If we did, you might find that half of the time an AC to AC match is really a no-match.

                              Comment

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