Finding Jeanie’s Father with DNA part 3: Identifying a Familial Cluster
Have you wondered how you can figure out which of your genetic cousins descend from a particular line on your family tree? Or maybe you have hit a brick wall in your genetic genealogy and are wondering what else you can try. In this post, I will explain the importance of identifying a familial cluster to solve your research objective and hopefully break through that brick wall. I will also continue the story of how I found my grandma’s biological father.
I hope that you are beginning to feel more comfortable with your DNA research skills By this point you should have your DNA results and have started a DNA research log, which I described in the last post. Be sure to check out my first post if you need more information about who to test.
After you have familiarized yourself with your DNA results and The Shared cM Project tool, the next step is to sort your DNA matches into groups based on their shared most recent common ancestor (MRCA). Family Locket blogger, Robin Wirthlin, gave us ten ways to do this. Third-party tools like the ones she described even do a lot of the work for us! The most important step in this process in this is to have a solid research objective so that you can quickly identify which familial cluster(s) will answer that objective.
Let’s say that your research objective is to confirm your link to your great-grandfather. You notice a cluster of six matches, four of which have the same surname as your great-grandfather. When you compare your shared centiMorgans (cM’s) with the members of the cluster, you see that one of your predicted relationships is second cousins! One of the matches has uploaded a tree, and it shows that they are also descendants of your great-grandfather.
Remember, DNA evidence can’t stand on its own. You should find a paper trail that connects your matches to their stated ancestors. Online family trees are a great start, but there can still be errors. Take it slow, and be sure you have enough evidence before you make a conclusion.———–
When I researched my grandma’s case, I used the shared matches feature on Ancestry to identify my familial clusters. Thankfully, many of my family members had tested so it was easier for me to identify the clusters and who their MRCA was. Through process of elimination, I identified a cluster of three individuals that descended from my grandma’s paternal side which was exactly what I was looking for! One of the matches had no tree, one had a “stub tree”, and one had a very full tree.
I reached out to all of these matches and introduced myself. I briefly explained that I was searching for my grandma’s biological father and asked if they had any information. If you’ve never reached out to cousins on a genetic testing service, check out this blog post for some ideas on what to say. Especially in cases of adoption, it’s important to be respectful and sensitive to those you are messaging. None of the people I messaged had any information that was helpful in answering my research objective, but they seemed curious about our connection.
Next, I created a private tree on Ancestry for those matches and located their MRCA using the information on their trees and research in census and vital records to fill in the gaps. If you decide to create a tree on an online website such as Ancestry, be sure to set the tree as private since you will be dealing with guesses and living people. Do not use FamilySearch Family Tree or another crowd-sourced tree.
From there, I identified all of the children of the MRCA. There were eight children in the family, and each of my genetic matches descended from a different child. Then, I compared the number of shared cM’s with the estimates on the shared cM chart and concluded that one of the sons of the ancestral couple was my grandma’s father. My grandma was born in 1943, and all of the sons in the family were between the ages of 20-31 when my grandma was born, so the timing and ages fit well.
The family tree below shows the common ancestral couple, their children, and the DNA matches to my mother, and how my grandma fits in the tree. Green boxes denote living persons whose names have been anonymized with the exception of myself and my mother. The gray box, “Father X,” is the hypothesized father of my grandma, and is one of the six sons in the family.
It can take a lot of work and careful analysis to find a cluster of matches that descend from your focus individual, but the end result is worth it! Once you reach this step, you are much closer to solving your research objective. You may even have enough information to start writing a proof summary for your objective! In my next post, I will share different research strategies I used to determine which son was Jeanie’s father.