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Thread: Problems with Gedmatch X Matches

  1. #1
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    Problems with Gedmatch X Matches

    I've been looking through my X one-to-many on gedmatch, and when I click to view the one to one comparison, it comes up that there's no match. However, when I lower the threshold, the match appears!

    For example, I match someone called Pazyshko on the one-to-many at 11.4cM, but when I click the one to one, there's no match. However, when I lower the threshold to 5cM / 500 SNPs, we apparently match at 17.9cM / 1,558 SNPs! This has happened with a few of the matches I've clicked on. Someone named Kaisa I match with at 11.4cM as well doesn't match in the one to one, but when the threshold is lowered they appear as matching at 11.4cM - the same as they appeared on the one to many.

    Is there a problem with the one to one X matching? Or would these be false positives?

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    I would message John Olson about it, but be sure to supply the kit numbers and data before contacting him.. You could also check if it is located on an excessive/pile-up spot..
    Last edited by evon; 04-29-2018 at 05:19 PM.

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    Quote Originally Posted by evon View Post
    I would message John Olson about it, but be sure to supply the kit numbers and data before contacting him.. You could also check if it is located on an excessive/pile-up spot..
    I'll send him a message, thanks! What do you mean by pile up though?
    Last edited by Ais; 04-29-2018 at 06:18 PM.

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    Quote Originally Posted by Ais View Post
    I'll send him a message, thanks! What do you mean by pile up though?
    See here:
    https://anthrogenica.com/showthread....ritage-FTDNA-)

  5. The Following User Says Thank You to evon For This Useful Post:

     Ais (04-30-2018)

  6. #5
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    Did you figure this out? I've been wondering about it recently. My mom has a couple of matches like that, and I think that when you otherwise match the X match will show based on the 500/5 thresholds. When I just click on X it's not there, but when I lower the thresholds it is.

    This is important to me to figure out, as my mom has a significant new X match (but low total match -- one other chromosome, probably about 4th or 5th cousin) who also SEEMS to have a significant X overlap with my mom's second cousin (female) on FTDNA. As I understand it, I can't tell from the FTDNA overlap whether the new match is a real overlap with the cousin, since one could be on one of my mom's X chromosomes, one could be on the other.

    I checked to see if the new match and the cousin are "in common with," but they aren't, not surprising because FTDNA seems to exclude the X in calculating those and the match on the other chromosome is not shared with my cousin. And besides the match is not high and "in common with" only works to a certain level.

    If the match is shared with the cousin it would be important, as then I'd know that it's through my mom's Swedish side, and specifically her paternal grandmother's parents. I have some small X matches in Sweden who show up but then have the matches that only work if I change the thresholds. They also match the new match (who I found on Gedmatch, unfortunately the second cousin is not there), but again only if I change the thresholds. If I compare my mom, the new match, and 2 Swedish matches, they all do seem to overlap on the X. But I can't tell if this is enough to conclude the new match IS on the Swedish side and the FTDNA overlap is real, or not, because the Swedish X matches could just be false matches.

    I am somewhat thinking that a significant X match (the new match is 14.8 on the 9, but 57 on the X, with longest segment of 49.9) from that far back perhaps leans more in the direction of it being paternal grandmother's parents (and maybe paternal grandmother's father's mother or the like) vs. my other most likely option, which is through her maternal grandmother's mother's parents (other lines have been largely ruled out), as the latter would have an awful lot of potential recombination to still be so significant.

    Any ideas?

  7. #6
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    I've been having the same problem with finding any matches using default settings. I have to move the SNP to 100 to find any matches, most of the time, I also have to lower the cM down to 5 as well. the X-one to many actually doesn't come up with any matches for me the last few days. :/
    GedMatch Numbers:
    - 23andMe (regular) M242790 (Genesis) SR4885234 <Same Test, I didn't know I had to upload to Genesis as I am on Chip V. The regular is for 1-1 only>
    - Ancestry: A707709

    Ancestry Username: valerieanne84

  8. #7
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    Quote Originally Posted by ValerieAnne View Post
    I've been having the same problem with finding any matches using default settings. I have to move the SNP to 100 to find any matches, most of the time, I also have to lower the cM down to 5 as well. the X-one to many actually doesn't come up with any matches for me the last few days. :/
    My X one-to-many was fine yesterday.
    Hope yours gets well soon.

  9. #8
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    Quote Originally Posted by Saetro View Post
    My X one-to-many was fine yesterday.
    Hope yours gets well soon.


    Thank you. The only person I don't have to change the settings for is my grandma, everybody else (including 1st cousins, etc..) I have to change the settings all of a sudden. one-to-many was still messed up for me today. Hopefully it's fixed soon (for me). Will probably check again before bed.
    GedMatch Numbers:
    - 23andMe (regular) M242790 (Genesis) SR4885234 <Same Test, I didn't know I had to upload to Genesis as I am on Chip V. The regular is for 1-1 only>
    - Ancestry: A707709

    Ancestry Username: valerieanne84

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