Monday, February 27, 2012

Why Y-DNA?

   I talk about using DNA for genealogy often.  My favorite is the Y-DNA test.  It has the largest number of benefits for the researcher.  I also get quite a few discouraging comments about Y-DNA.

   Recently I was told that Y-DNA marker mutation rates were too unstable.  The comment might give the impression that Y-DNA testing was unreliable or unusable.  This is far from the truth.  The marker mutation rates are exactly what makes Y-DNA so valuable.  Without the mutations, we would all be one big happy/unhappy haplogroup.

   Another comment I hear is that Y-DNA only tests your paternal line and that is just a small fraction of your genealogy.  This is true.  But...

   My genealogy is more than just my paternal line.  I’m sure many of us can’t help but to associate deeply with our paternal line, our surname.  That deep association makes getting the Y-DNA test so important.
That doesn’t mean that I’ve stopped with my DNA.  I’ve also collected my father-in-law’s DNA.  I am planning to collect DNA from my mother’s male line and my mother-in-law’s male line, etc., etc.  It’s very possible to collect samples for hundreds of your surnames.  See the second half of my post on NPEs.

Here is a short list of reasons to get your Y-DNA tested:

   Cultural origins:  We focus a lot of our time on nationalities.  I’m Italian or I’m Irish.  Your nationality will only take you so many years into the past, depending on how old your nation is.  DNA testing (y-dna and mitochondrial) allows you to go further back in time to a cultural heritage – celtic, norse, phoenician or native American as examples.  Between my Y-DNA and my autosomal tests, I can tell you which Caucasus Mountain culture that I relate to.

   Traditional research validation:  You can have a great paper trail and have a bad genealogy.  There will be non-paternal events.  When you compare your Y-DNA test for your surname Brown and all the other matches, across a half dozen databases, come back with the surname Brown you will feel confident about your research.  If your matches come back with the surname Green, then you will have some work to do.

   Traditional research to find Y-DNA:  You will need to use traditional research to find all those cousins you need to get samples from.  You can also use your existing research to find the Y-DNA of your ancestors.  Typically every DNA database asks for the most distant paternal ancestor (Y-DNA) or maternal ancestor (mito).  If you search for your ancestors among these records you will then have the results of a test someone else has already completed.  I will be posting a mini-webinar on this subject to walk you through the process.

   Adoption research:  In the case of adoption, you are hoping to get that surprise surname.  In my research, I ran across a person by the name of Tom Doty.  In his profile, he stated that he had been adopted.  What made him stand out was that his DNA matched so closely with a very large Dodge surname study.  I contacted him and pointed him in the right direction.

   Discover living relatives:  Every match is a connection to a living cousin.  Odds are pretty good that one of you can help the other connect the dots on your common ancestry.

   Mapping your tribe:  As I mentioned earlier, it is the mutations in Y-DNA that give it the most value.  Using those mutations, you can trace your ancestors across time.  Using readily available tools, you can calculate that you and a group of individuals have a common ancestor 1000 years ago or 2000 years.  Map the ancestral locations of that group and look for patterns to emerge.  I will be giving a talk on this subject in March.

   All DNA tests have their pros and cons.  With a good understanding of the possibilities and the limitations, we can develop some new tricks that the DNA companies have never thought of.  If there is one thing that I have learned, it is that genealogists are very resourceful.


  1. My question is this. I have a hard time understanding the Dna and how to read it and know it. My question is this. How can i have so many seemingly good DNA matches but not one with my Name? Everyone has a different last name. I need it explained to me. Thanks

  2. I got my yDNA test back recently(G2a) and it says some 16,000 ya my branch was in the Middle East then moved North as "Caucasus Mountaineers", then N. Poland and W. Germany. How sure are researchers about these 'way points' and is there any tome I can read that will give me more than cursory information. (I found a relative that lives in Poland).

    1. @Starmon - I am also G2a. Every DNA site and wikipedia will give you a cursory description of haplogroup G origins. These researchers can paint with a broad brush and they will be close on the haplogroup as a whole. New info and research comes along all the time that helps refine our picture.

      To actually get close to identifying the 'way points' you need to research at the haplotype level. Where were your closest ancestors at different periods in time.

      My haplotype tells a story of a migration from the Caucasus Mtns, up the Danube to its source, then over to the Rhine. At the Rhine my tribe splits north and south.

      To my knowledge there is no literature on how to figure out how your ancestors got from point A to point B. I have developed a technique for mapping haplotypes across time.

  3. @Frank - I have questions right back at you. How many markers have you had tested? When I first had my DNA done I only did 12 markers. Lots of matches - no matching surnames. As I learned more, I found that 12 markers will really only give you ancient homelands and haplogroup. If you don't have a surname match at 12 you won't find one with more markers. If your surname is rare like mine (Maglio) then you may want to start your own surname study.

    Now if you already have 37+ markers tested and you start to see the same surnames popping up frequently with an exact match then its time to pinpoint where in history your name changed.

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