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Making Sense of Your Matches on Ancestry

   I’m going to use Ancestry for this example, since it has the largest database.  The process, however, will work with other testing companies as well.  As I mentioned earlier, I wasn’t sure why I should test, and once I did, how to make sense of all of my matches.  Some of you may be in the same situation.  

   DNA is another tool in our genealogy toolbox.  I’ve talked a lot this year about having a plan when you research.  There is a difference between researching and surfing.  DNA is no different.  What is the question you are trying to answer?  What made the difference with me was moving from a passive mode…who are all these DNA matches…to an active mode, who do I need to test to answer my research question.  

   Here’s just a reminder about how atDNA works.  You get approximately 50% of your DNA from each of your parents.  Since they got 50% from their parents you carry about 25% of the DNA of your grandparents and it continues…12.5% of your great grandparents; 6.25% of your 2nd great grandparents, etc.  I’ve referenced the ISOGG Wiki quite a bit during this discussion, and the two charts I use the most are the “Average autosomal DNA shared by pairs of relatives” and the “Cousinship Chart.” In both cases, read the entire article.  Blaine Bettinger’s “Shared cM Project” on the average autosomal page is very interesting as you can see the wide variation in specific relationships. The charts represent the average, but how many of us are average!  This was the information I was able to use to determine the relationship between Jack Moughty and my husband that I wrote about a few weeks ago.

   So now that you understand how you inherit your atDNA, let’s look at some examples from Ancestry.  One of my first efforts was to get a 1st cousin to test on both my maternal and paternal lines. My parents, aunts and uncles had all passed away before I started looking at DNA.  Luckily, I had at least one cousin on both sides who had an interest in genealogy.  My maternal cousin had already tested, along with her brother and nephew in an attempt to identify someone in their father’s Swedish line.  After a conversation with the paternal cousin, he also agreed to test.  So here are my results after the cousins tested.  Note that prior to their tests, I had no match closer than 3rd cousin and other than a couple of individuals I had communicated with in the past, had no idea how to determine a relationship.

   Once you have an identified 1st cousin match, look at the match, in this case, my maternal 1st cousin.

She is predicted to be a first cousin (which is correct).  This is based on the number of cM of DNA we share.  To find out that number, click on the “i” in the circle after the relationship.  It tells me that we share 876 cM of DNA across 40 segments.  This does not provide as much detail as some of the other sites, but enough.  According to the ISOGG chart, an average of 850 cM could be “First cousins, great-grandparent/great-grandchild, great-uncle or aunt/great-nephew or niece, half-uncle or aunt/half-nephew or niece.”  Blaine Bettinger’s Shared cM Project (just scroll down a bit farther) indicates 1st cousins can share between 553 and 1225 cM’s with the average from his study being 874, so we’re right in the ball park.  I use the Notes field to indicate the known relationship.  I might add other notes regarding contacts with this person, emails sent or most recent common ancestor.  Next I look at “Shared Matches.”

   Since we are maternal 1st cousins we share our maternal grandparents, in this case the surnames Beighton and Moag. If I click on “Shared Matches” I will get a list of those people who share with both my maternal cousin and myself.  That would mean that those matches are probably on my maternal side.  For illustration purposes, I have typed in the most recent common ancestor for known relationships.  

   In the case of McDowell/Shaw match, I have corresponded with this person in the past and we established the common ancestor.  Since we both have trees on Ancestry, we also have a shared ancestor hint matching our trees showing that we are 3rd cousins (not 4th cousins as predicted).  

   I have also had contact with the person identified as a Moag/Rush match.  Her tree only has 19 people and is locked.  If I didn’t already know her, I would have had to write and ask her to share information.  She, too, is a 3rd, not a 4th cousin.  

   So by having a DNA test on a 1st cousin to compare, I can break down most of my matches to either my maternal or paternal side.  If I now look at shared matches with my McDowell/Shaw match, I can further break down my matches to those who are likely related on the McDowell/Shaw line.  The same on the Moag/Rush line.  

   So does my match list contain everyone who tested and is related to me?  The answer is no.  Because DNA is passed down randomly, you may not have received a specific piece of DNA from an ancestor.  It is estimated we will only share about 50% of our DNA with 4th cousins. Here’s an article by Diahan Southard. If you have tested siblings you can see this as you may share varying amounts of DNA. For example I share 2,545 cM with one sibling and 2,401 cM with the other. So even though we inherited about 50% from each parent, it can be a different 50%. 

   To be effective in using your DNA results, you need to have a plan…just like all of your other research.  Look at your tree and identify your ancestral couples (the numbers to the left denote the level of cousin).  Work to identify descendants of that couple.  If you’ve focused just on your direct ancestral lines, this is the time to expand your research.  The more you know about the extended family, the more likely you might be able to identify an existing match on your DNA list.  Then look at your shared matches to identify others likely descended from that ancestral couple.    

    If you don’t have any close cousins who have tested, this might be the time to approach them about testing. It may take purchasing the DNA kit for them and now is a great time to buy those extra tests with the Ancestry Holiday Promotion. Make sure you fully explain the test to those you would like to participate.  Some may be willing to jump right in and others may be hesitant.  Don’t try to force anyone.  There are both positive and negative aspects of testing and anyone you test should fully understand the implications.  DNA tests can provide surprising results, such as unexpected parentage, cousins who perhaps were given up for adoption, or can destroy a cherished family story or tradition about ethnicity.   Read the Genetic Genealogy Standards that have been developed by a group of genetic genealogists to provide an outline of best practices for the community.  Also check The Legal Genealogist blog by Judy Russell.  Judy separates the alarmist voices from actual facts when it comes to DNA.

   I hope this has been helpful for those of you who are still trying to figure out how to use your matches. Feel free to leave a message on my Facebook page with any comments.  I’m always hoping to learn more.

   Happy Hunting!

Just a reminder that registration for the Ireland Research Trips is open.  To date both trips are over half booked, so if you would like to join us, download the registration and send it in as soon as possible.



© Donna M. Moughty 2007- 2017