When genealogists take an ancestry DNA test, they are looking for more than just your ethnicity. They are also very interested in receiving their information on other people who have tested who closely genetically match them. They want to know who the closest matches are and if the match has family tree information that they can share.
However, with all the people testing these days, the volume of matches can become overwhelming very quickly.
Are you one of those people have have way too many genetic “4th cousins or closer” among your DNA matches? Have you ever wondered “What do you even DO with all those matches?” That is the question we are going to answer today.
Doing the DNA Math on Your Cousins
However, the farther back we go the less we can rely on math. For example, on paper you should have 64 3rd great grandparents. However, many of us find that the same person occupies more than one slot on our pedigree chart. While this significantly decreases the workload for traditional genealogy, it adversely impacts your genetic genealogy. Especially when it comes to that long long list of 4th cousins you have in your match list at any of the three major DNA testing companies.
Depending on how intermarried your lines are, you may be seeing individuals on your match list that genetically look like your fourth cousins, but they are genealogically your sixth cousins – EIGHT TIMES! So how can you tell the difference?
There are two parts to that answer: one you can control, and the other you can’t.
Distinguishing DNA Matches with Genetic Tools
While your fourth cousins and your eight-time-sixth cousins may look similar genetically, there are often small clues in the genetics that can help you tell the difference. This distinction can sometimes be detected by a testing company who, through research and validation, has been able to fine-tune their algorithms to detect these subtle differences.
You can participate in this double checking process by using some of the genetic tools that are available to you at Family Tree DNA, or at Gedmatch.com. But since most of you are not aspiring geneticists, let’s focus on the genealogical work you can do to determine if a match is truly a fourth cousin.
Use Google Earth to Plot Your DNA Matches
A fourth cousin designation just means that you and your match are separated by between six and twelve degrees (people). So that might be five back on your chart to your common ancestor, and five down to your match, which would make you true fourth cousins, or it could be some other permutation of that.
For our example, let’s assume true fourth cousins. That means that the two of you share one of 32 3rd great grandparent couples. In order to find out which set, you have two genealogical identifiers: surname and location.
Therefore, the first thing you should do is make a list of the 32 surnames and locations of those couples. If you want to be an over achiever, make a list of all 64, which would include the maiden names of the ladies.
Now, most of us do not know all 32 of those couples, so you are going to have some holes. Feel free to fill in those holes with surnames on subsequent generations that will carry through to this fifth generation.
You can create a folder in the Places panel in Google Earth and devote it to your 32 couples. You can then easily plot your surnames and locations. Simply search each location and place a placemark in that location by clicking the placemark button in the toolbar at the top of the Google Earth screen (it looks like a push pin.)
Then evaluate the fifth generation of your fourth cousin matches for genealogical information that lines up with any of the items on your list.
You can also plot the surnames and locations of your matches in Google Earth. This is where Google Earth really comes in handy. The free software makes it very easy to see when your ancestral home may be bordering the locations of your matches. Those with whom you find a similarity become your best matches, and your best chance of determining your connection. Those without an obvious connection cycle to the bottom of your pile for a genetic evaluation, which we will cover next month. You can perform these same kinds of searches for your second and third cousins as well.
As you begin to become more familiar with the fifth generations of your matches, you may also start to see patterns of surnames or locations emerge among your matches. These then become the surnames and locations that might be able to fill the missing spaces in your pedigree chart.
More Genetic Genealogy and Google Earth Gems
If you are new to using Google Earth, I have several suggested resources for you by Lisa Louise Cooke:
- How to Use Google Earth for Genealogy (FREE VIDEO)
- Google Earth for Genealogy Video Training digital download
- If you are a Genealogy Gems Premium member, Tune in to Genealogy Gems Premium podcast, episode 131, for tips on how to run a more thorough genetic evaluation on those 4th cousin matches.