X-Chromosome Matching at Family Tree DNA

Just as they promised, and right on schedule, Family Tree DNA today announced X chromosome matching.  They have fully integrated X matching into their autosomal Family Finder product matching.  This will be rolling live today.  Happy New Year from Family Tree DNA!!!

In the article, X Marks the Spot, I showed the unique inheritance properties of the X chromosome.  In a nutshell, men only inherit one copy from their mother, because they inherit a Y from their father, but women get a copy from both parents.  Still, you don’t inherit parts of your X from all of your ancestors, so knowing your own X inheritance pattern can help immensely to rule out common genealogy lines when you match someone on the X.

In their informational rollout, Family Tree DNA provided the following information about their new features.

Here is the menu link to the Family Finder Matches menu.

x match 1

On the Family Finder Matches page, there is a filter to show only X-Matches.

x match 2

When you use the X-Match filter on a male Family Finder kit, you should get only matches from the maternal X-Chromosome.

x match 3

Next, like other Family Finder Matches you can expand the advanced bar for a match and click to add the match to the Compare in Chromosome Browser list.

x match 4

Matches are added to the Compare in Chromosome Browser list. You could go right to the Chromosome Browser by clicking on the compare arrow at this point.

x match 5

Next we can also go right to the Chromosome Browser.

x match 6

The Chromosome Browser also lets you filter the match list by X-Matches.

x match 7

Here are three immediate relatives. The first two share X-Chromosome DNA. The third (green) one does not.

x match 8

When we scroll down to the X at the bottom, we see that X-Matching is displayed for the first two but not the third.

x match 9

Moving to the Advance Matching page, X-Chromosome matches have also been integrated.

x match 10

X-Match is an option that can be checked alongside other types of testing.

x match 11

151 thoughts on “X-Chromosome Matching at Family Tree DNA

  1. Hi Roberta,
    I am adopted and am very new to DNA. I had both my MtDNA and Family finder test done at Family Tree DNA as well as Ancestry and 23&Me. With FTDNA, I have many x-matches, but only two men. One is a 4th-remote cousin and the other is a 5th-remote cousin. After reading your information about the x-chromosome, I understand that the only way that these two men can be related to me is through my mother’s line. What is my next step? Do I concentrate on their common matches with me (though neither of them share matches with each other), or should I look at their shared matches with me and only concentrate on x-matches from that point?

    I started looking at both men on the chromosome browser and noticed that they match in the same place on the x-chromosome as well as 3, 6, 11, & 12. I started comparing chromosomes of other x-matches and found that many matched on the same segment of the X and 11 chromosomes, though they only show up at the 1cm range. I am not sure what to do with this information though it seems as though I might have found something important.

    Should I keep working to identify everyone that match in the same segment of the X and 11 chromosomes and then compare them with some tool like dnagedcom or something? Should focus only on people with the longest block (over 20 to my match max of 53); or highest shared Cm (over 50 to my match max of 70); or only my x-matches with the longest block or the highest shared Cm?

    I started looking at my 2nd-4th cousins and looking at matches I had in common and writing down all my x-matches from there, but I understand that this won’t tell me whether the match is on my mother or father’s side. I had 1 person (5th-Remote cousin on family finder) who matched from my MtDNA and looking at the matches we have in common, there are 2 X-matches (neither of them are the 2 male X-matches). Then when I click on those X-matches, I get more. I’m lost. Do I just keep adding the X-matches of my X-matches?

    I can see how the X-matches will be very important for me, but I don’t know what they actually mean for me since the two male X-matches and my one MtDna match are so distant. Is it worth pursuing or should I go back to my 2nd-4th cousin matches or keep looking at chromosomes (especially #11 where so many are stacked)?

    Sorry for this really long question but i am SO confused!! I hope you can give me some advice and/or point me in the right direction … or give me some links so I can learn more.


    • I generally work the X chromosome last. FTDNA only lists your X matches who also match you on another chromosome. I start with what I do know and with my largest matches and go from there. You need to join the adoption DNA group. Look under the help tab at the top of my blog page. They have a process for you to work through that you will find very helpful. Best of luck to you in your search.

      • Thanks! I was getting overwhelmed at the extra information from the Chromosome x and trying to figure out what that data meant. I did think that I could narrow down my search to just my maternal line from it and then go back to largest matches. However, I will do what you said. I appreciate the help!!

  2. I only have one X match out of 400+ matches. That sounds low or is that normal? And it would be on my mothers side correct? All of her roots are in the south which puzzles me as most of my mtDNA is Native America or French Canadian with a small portion of Ulster Irish into Pennsylvania.

    Another question: I’m looking to find a unknown maternal grandfather for my daughter. Some of her matches I know are on her maternal grandmothers side, She has one close match where that person matches on a number of chromosomes plus the X. I have no clue who she is because she didn’t put any identifying information on the site. I have a birth certificate and oral history that don’t match. I need to e-mail her I guess but I have to wordsmith it carefully as I don’t want to upset someones DNA tree with something that has been hidden in the closet for years. Anything I should be looking for in the DNA?

    Thanks for any help.

    • Hi Roger. You only get X matches if you also match that person on other segments as well. That is why the number of X matches are so low.

      Yes, it would be on your mother’s side. Good luck on your second quandary. I would tread lightly and see if you can establish contact first.

  3. My wife wants to find her roots in England and Russia or perhaps Germany through her fathers family lineage (x chromosome testing) We live in North America and she was born in Poland. Her father died when she was very young and had no contact from that side of the family. She really wants to know where her paternal grandmother came from. How accurate will the results be using the x chromosome test?

    • The X chromosome will not be of any special us for this. The rest of the autosomal DNA will be of more use. Finding her father’s lineage will be the easiest if she has someone, like her mother or a sibling of her mother to test, so she can tell who is from her mother’s side. Any of her father’s relatives would be good to test too.

  4. Roberta, quick question (sorry if it is stupid, I’m new to all of this). As a female, do my x-matches match up with both sides, since I receive x from both parents, or would my results be indicative of my mother’s side only? I’m completely confused. I’ve got 12 pages of x-matches on FTDNA. THANKS!

  5. How useful are the cM lengths on the X chrome in trying to narrow relationship range?

    I’m trying to figure out a family mystery surrounding an Italian great-grandfather. Both my father (Chas) and his first cousin (Endicott) have a common female match (Ann) who is estimated 2nd-3rd cousin. Endicott and Ann match on two places on the X for at 45.5 cM and 29 cM. for a total of 74.5 cM. Endicott’s mother and Chas’ father are siblings. Hence that’s why Endicott has an X match with Ann and not Chas. Can I use the 74.5 cM X match to solidify the estimated 2 – 3rd cousin match estimate? Other data for the matches:

    Endicott to Ann – 218 cM Autosomal on 21 segments with largest 4 at 38cM (6204SNP), 36 cM (10,300 SNP), 27cM (5649 SNP) and 19 cM (4400 SNP). Of the 21 segments, 7 are under 5 cM.

    Chas to Ann – 240 cM Autosomal on 17 segments with largest 4 at 50cM (8153 SNP), 33 cM (4566 SNP), 32 cM (6786 SNP), and 25 cM (4729 SNP.) Of the 17 segments, 6 are under 5 cM.

    My limited knowledge tells me that Chas/Endicott must be 2nd cousins to Ann with very little chance that it’s an outlier to 2nd cousin 1X removed. Thank you so much for any insight you may have.

    • I would rely on other information from other chromosomes primarily. I have found the transmission characteristics of the X to be somewhat different than the rest of the chromosomes so I could be hesitant to apply the same guidelines to the X as to the other autosomes. I don’t believe Blaine Bettinger included the X in his cM study, but it would be very interesting if he were to do so.

  6. Okay so two questions.
    1. I have one of my parents and my kit on here. My dad. If I run in common matches only that are x-match, would those all be relatives from his mothers side?

    2. If I run to exclude all common matches with him, woudl those x-matches all be from my mothers side?

    I think x-match is pretty darn cool. It makes the autosomal have some teeth. How did they do it though after all the hee haw about how they leave off that?? Why are they unable to get the haplotype from the same test?


  7. Pingback: DNAeXplain Archives – Introductory DNA | DNAeXplained – Genetic Genealogy

  8. Hi,

    Would you be able to tell me what the significance of each chromosome strand? I am just getting started and just want to know when there are matches on particular chromosomes if that has any particular meaning.

    Thank you

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