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  1. #1
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    Default Autosomal testing and DNA recombination

    One of the most commonly misunderstood aspects of the autosomal DNA test, it is not a one stop shop kind of DNA test to tell you everything you need to know. The autosomal DNA test has limitations to what it can, and can not do for you.

    DNA recombination is a subject that tends to not get as much attention as it should. It is because of DNA recombination, exactly explains why you are an autosomal match to some family members, but not a match to other family members. You would not know you were not a match to a distant cousin, because they will not show up in your match list.

    Some times it takes a DNA project Administrator to be able to show the DNA participant that he / she is not a match to a paper trail proven cousin, for that DNA participant to even know they were not a match to that cousin. To show people how DNA recombination plays a roll in our autosomal DNA matches, I built a chart using my own family members as the example. There are 10 of us family members in this example, though there are a lot more of us autosomal tested but not used in this example.

    I picked out 10 closely related family members and distantly related family members as the example that I am about to share. In this example, I share to the exact degree of kinship each family member are related to one another.

    Example 1.

    Donald is a 2nd cousin 3x removed to Jacob, they are not a match
    Donald is a 3rd cousins 1x removed to Laura, they are a match
    Donald is a 4th cousin to Donald D., they are not a match
    Donald is a 6th cousin to Crystal, they are not a match
    Donald is a 4th cousin 1x removed to John, they are not a match
    Donald is a 3rd cousin 2x removed to Debra, they are not a match
    Donald is a 3rd cousin 1x removed to Allison, they are a match
    Donald is a 2nd cousin 2x removed to David, they are a match
    Donald is a 4 cousin 2x removed to Kenneth, they are not a match

    Had all those family members only relied on autosomal DNA to find related family members, they would have been disappointed because they would not have found those family members using only the autosomal DNA test to find related family members.

    DNA recombination plays a very real roll in who you do, or do not match with, and you would never know whom it is you are not a match with, because they will not show up in your match list.

    Okay so how is it I know who matches me, and does not match me you might ask?
    I know because I am a surname DNA project Administrator, I get to see ALL the members test results whom are project members, so I have an advantage that most of you do not have.

    You may actually have far more family members whom have been autosomal DNA tested then you know about that you are not a match to, and you would not know it because they won't show up in your match list.

    It is a common misconception if you are not a match to someone, then you must not be related, which is a false assumption! The more distant the kinship is, the less likely 2 paper trail proven family members will be an autosomal DNA match to each other due to DNA recombination.

    I then used each participants matches to build another list for each of the 10 family members to show who they are or are not a match to.

    Example 2.

    Jacob is a 2nd cousin 2x removed to Donald D., they are a match.
    Jacob is a 2nd cousin 3x removed to Donald, they are not a match
    Jacob is a 2nd cousins 2x removed to Laura, they are a match
    Jacob is a 3rd cousin 3x removed to Crystal, they are not a match
    Jacob is a 2nd cousin 2x removed to John, they are a match
    Jacob is a 2nd cousin 2 time removed to Debra, they are not a match
    Jacob is a 2nd cousin 2x removed to Allison, they are a match
    Jacob is a 2nd cousin 1x removed to David, they are a match
    Jacob is a 3rd cousin 1x removed to Kenneth, they are not a match

    I did this for all 10 family members and each family member had different results with whom they did or did not match with.

    Regardless how strong your paper trail records are proving kinship, DNA recombination clearly plays a roll in whom you will or will not match with, and when you learn a distant cousin is not a match, that no match may wrongly give you the false impression you can not be related to them, which simply may not be the case if you are not comprehending how DNA recombination is affecting your autosomal DNA matches.

    Now most all the men mentioned in that list, have also been Y DNA tested and they are all a Y DNA match to each other! Y DNA clearly told a very different story! This is why it is vitally important for the men of your family to also consider doing the Y DNA test on top of the autosomal test.

    Cousin Crystal descended from a different branch of the family tree way back in the tree, and she does not match the other 9 cousins! Again, had Crystal only relied on autosomal DNA, she would not have found those other 9 distantly related cousins because she is not a match to any of them.

    All 10 cousins share the same common male ancestor born in 1767.

    It is also very important for DNA participants when posting to various forums, to not just say you have been DNA tested because there are 3 main types of DNA testing.

    Autosomal DNA ( for males and females )
    Y DNA ( male only test )
    mtDNA ( for males and females )

    Each type of genetic genealogy ( DNA ) test has it's own purpose and when you restrict yourself to a single type of genetic genealogy test like the autosomal test, you are limiting your knowledge just to that one type of test, a test that clearly has limitations due to DNA recombination.

    In our case, we already knew well in advance before being autosomal DNA tested that we were all related to one another, we have been in contact with one another for decades.

    And unfortunately, far to many DNA participants tend to jump to the NPE = Non Paternal event, which can mean adoption, surname change or what ever the cause is to cause a family member to not be a biological descendant if they don't match their distantly related family members because they do not clearly understand how DNA recombination plays a roll in our autosomal DNA matches.

    When you start getting in to say the 2nd cousin how ever many time X removed kinship range, DNA recombination plays a roll and it is pure luck of the draw whom you will or will not be a genetic match to.
    This is why I always encourage participants to also include the Y DNA or mtDNA tests, because those tests can tell you things that the autosomal test simply can not tell you.

    5 of the men in those examples are of the same surname, all related back to the same common male ancestor born in 1767. All 5 of those men were Y DNA tested and were a Y DNA match to one another, proving they did indeed descend from the same common male ancestor. But again, if those 5 men only relied on the autosomal DNA test, they could wrongly believe they are not related because not all of the men in the examples were an autosomal match to one another. Y DNA told us a very different story then what the autosomal test had to tell us.

    When autosomal DNA participants limit themselves to that one single type of test, you are not seeing the bigger picture.

  2. #2
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    Great advice although you don't explain what recombination actually entails. My limited understanding of the subject suggests that what you are referring to is that although we each inherit roughly half our DNA from each parent and our siblings do likewise but not necessarily the same half. So as you go backwards in time even though you may share the same great grandparents you may not match DNA wise. Is that close?
    "People will not look forward to posterity who never look backward to their ancestors.” Edmund Burke

  3. #3
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    In simple terms DNA recombination is the process that makes us individuals rather than clones of our siblings.
    Cheers
    Guy
    As we have gained from the past, we owe the future a debt, which we pay by sharing today.

  4. #4
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    Autosomal DNA in a nut shell, is totally random.

    If say two siblings were autosomal tested, each sibling may have matches that their other sibling does not have, so even between siblings they may not get the same autosomal matches due to DNA recombination.
    Each sibling inherited different autosomal DNA from countless ancestors.

    There are web pages and I think videos online that better explains DNA recombination.
    I was just pointing out to everyone that they may have more cousins autosomal tested then they know about and that they would not find certain cousins because the are not a match to you.

    Y DNA is especially important in genetic genealogy for our direct paternal trees. Y DNA does not have the same DNA recombination issues and Y DNA is considered one of the most stable pieces of human DNA for that very reason, that it does not have the same recombination issues.

    It is when we combine autosomal DNA, Y DNA, mtDNA, and our paper records research, can we broaden our knowledge over all and be able to see a much bigger picture in the long run.

    When participants limit themselves to a single type of genetic genealogy test, they are not seeing the bigger picture.

    What I did not fully explain in my original post is, there are a better part of 20 of us paper trail proven cousins of the same surname whom have been autosomal DNA tested, and there are 18 men of my paternal lineage Y DNA tested who range in kinship from father and son, to as distantly related as 6th cousins.

    There is so much more to learn with genetic genealogy then just autosomal DNA test.


    Guy Etchells said it nicely, if we all inherited the exact same DNA, we would be clones instead of individuals.

  5. #5
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    Yes, people are quick to cry out the NPE old chestnut (informal adoption, extra marital dalliance) and that can be dangerous talk. I think such occurrences were pretty rare, it was different times back then.

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