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Got my results - Need advice

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  • Got my results - Need advice


    I am still trying to understand DNA testing and genealogy and this is still relatively new to me. Forgive me if I ask any stupid questions since I have been trying to decipher my data since I got it yesterday.

    A little background on me. Since I have been doing genealogy research, there have been people that have stated that my family line is related to another line with the same surname. Other local researchers on my surname never really agreed that we were related to this line but couldn't prove it. The other line has done DNA testing on their side and asked me to join them and submit a DNA sample. The results I got pretty much proved we are not even closely related. I think there was agreement on 7 out of the first 12 markers.

    I have now looked around and found a possible match and have some questions:

    1. On comparing the 25 markers, we agree on 24 and the other one was 1 off for a genetic distance of 1. Even though he has a different last name, would there be a strong chance that we are closely related? From some articles, it seem to imply that having different surnames reduce the chances of being related.

    2. This common relative might be 12 to 16 generations back, would this be correct based on the info in item 1?

    3. The differenence between us is the DYS 19/394 marker. Is this a significant marker or would this be a marker that could change through the different generations? What does this marker represent, if anything?

    Thanks for your time.

  • #2

    Any marker can mutate at any time -- it's completely random. Some markers mutate more frequently than others, but that doesn't mean a "slow" marker couldn't have mutated recently. A father and son could have a difference on a slow marker. It's just the luck of the draw.

    When comparing yourself to someone who has a different surname, it's best to compare at least 37 markers, and 67 is best if you can. At 25 markers, there's too often the chance of a coincidental match that can fall apart once you upgrade.

    It also depends on your haplogroup. If you're in R1b1b2, then you definitely want to test as many markers as possible and also consider deep-clade testing. This is the most common haplogroup among western Europeans, and it's very easy to look like a match with someone who you're not recently related to when you don't test enough markers. It's also possible (rare, but it has happened) to closely match someone who happens to be in a different subclade, but that different subclade tells you that the connection between you is thousands of years ago.

    This is the best I can give you without seeing your actual results. If you want someone to look at your results and give more specific suggestions, upload them to Ysearch using the link on your Y-DNA Matches page, then post your Ysearch ID (not the password!) here.

    Last edited by efgen; 17 March 2009, 12:06 PM.


    • #3

      Thanks for your response.

      I had my tests done on 37 markers but the other person only had 25 done.

      My haplogroup is R1a1 and by Ysearch ID is 88RUS. Any other suggestions would be helpful.



      • #4
        Hi Keith,

        OK, your R1a1 haplogroup changes things a bit.

        Unlike R1b1b2, which today has a huge number of subclades, R1a1 has only 5 (R1a1a through R1a1e). However, I haven't seen a single FTDNA customer test positive for any of those. So I do _not_ recommend the deep-clade test in your case.

        If you haven't already, you can join the R1a project. And you can see on the project's public website that no one has a designation beyond R1a1:

        With our premier suite of DNA tests and the world’s most comprehensive matching database...your DNA has met its match!

        This may change in the future if new useful SNPs (which define the subclades) are discovered.

        Now regarding your 24/25 match. I don't think the situation is quite as bad as R1b1b2 with regards to accidental matches, but still, any comparison on 25 markers can only give you so much information. According to FTDNA's chart below, a 24/25 match has a 95% chance of being related within 20 generations:

        That means anywhere from 1-20 generations (with a 5% chance of it being more than 20 generations). As I mentioned earlier, mutations can happen at any time. So a father and son could have a 24/25 match or even an 11/12 match or 36/37, etc.

        You'll also see on the chart that if you compare on more markers, the confidence intervals improve. A 1-marker mismatch at 37 markers (36/37) indicates a 95% chance of being related within 10 generations. Even a 2-marker mismatch at 37 markers (35/37) gives a closer timeframe than the 24/25 match -- 14 generations instead of 20 generations.

        If you were comparing with someone who had the same surname, then the 24/25 would definitely be a good indicator of a recent connection. But with the different surnames, you're missing that additional evidence (the surname), so the 24/25 match just isn't enough information to draw any better conclusion than you could be related within 20 generations.

        What you may want to do is contact your 24/25 match through Ysearch, share genealogy info, and if he seems amenable, let him know that you've tested 37 markers and ask if he would be willing to upgrade for better comparison. I believe the upgrade from 25 to 37 is only $49.

        Last edited by efgen; 17 March 2009, 01:52 PM.


        • #5
          Hello Elise,

          Thanks for taking the time to respond to my questions. I now have a better idea of how to look at my results. Next step is to contact the original person that I mentioned and a second person who seems to have a good match but with fewer total tested markers.