I am sure I am not alone in finding that I constantly have more to learn when it comes to using DNA in my genealogy research. For example, I have defined many situations in my DNA research as pedigree collapse. However, after reading Diana’s post Endogamy, Pedigree Collapse, and Multiple Relationships: What’s the Difference and Why Does it Matter? I realized that almost always, when I used the term pedigree collapse, I was actually describing multiple relationships.
Diana defines both pedigree collapse and multiple relationships in her post:
- “Pedigree collapse occurs when cousins reproduce, and their descendants have ancestors in more than one place in the family tree.”
- “Multiple relationships occur when you are related to someone on more than one of your family lines, so you have multiple common ancestral couples.”
I have actually rarely come across cousins marrying each other in my research, but there are many DNA matches that have multiple common ancestral couples with the test-takers.
The Case of Dan Smith and Martin Jones
An example of this complication came in a project I recently worked on for a client. FamilyLocket Genealogists has been working with this client for the past year to help her extend some of her family lines past 1870, which is a common brick wall for many African-American families. The
Initially, the project worked on finding the parents of the client’s great-grandfather, Dan Smith. DNA helped us discover that Dan Smith’s father was a white man, but we had not made progress on identifying Dan Smith’s mother. We decided to take a break on Dan Smith’s project while we gathered more DNA, and in the meantime, we started to research a great-great-grandfather of the client, Martin Jones.
As I began to research Martin Jones, I ran into a significant problem. Almost all of the client’s matches with Martin Jones’ descendants also matched Dan Smith’s descendants. As shown in the chart below, Dan Smith first married Emma Davis, and they had a daughter named Gertrude Smith. Gertrude Smith married Martin Jones’ son, John Jones. When Dan Smith’s first wife, Emma Davis, died, Dan Smith remarried Martin Jones’ daughter, Mary Jones. The client and the other test-takers descend from Dan Smith’s marriage to Mary Jones. As such, the descendants of Dan Smith and Mary Jones are sharing DNA with the descendants of John Jones and Gertrude Smith through both Dan Smith and Martin Jones.
This is an interesting case because, through the Jones line, the test-taker and the matches are one generation apart, but through the Smith line, the test-taker and the matches are two generations apart. A third cousin once removed is the expected relationship between the test-taker and the matches through the Jones line. However, the expected relationship between the test-taker and the matches through the Smith line is a half-second cousin twice removed. The average amount of DNA shared between 3C1Rs is 48 cM. The average amount of DNA shared between Half 2C2Rs is also 48 cM. However, the average amount of DNA shared between the test-taker, and the descendants of John Jones and Gertrude Smith is 84 cM. This is making these DNA matches appear to be more closely related to the test-taker than they actually are.
In this case, the main problem with this multiple relationship complication was that when the project began, only nine DNA matches who descended from Martin Jones had been identified, and they all came from the couple John Jones and Gertrude Smith. Therefore, when a network graph was created, all of Martin Jones’ known descendants and all of Dan Smith’s descendants showed up in the same cluster (Cluster 4 in the network graph below).
Even when this cluster was subclustered, all of these matches stuck together making it very hard to track which DNA matches may lead to Martin’s parents.
By sifting through matches and building out trees, three DNA matches who descended from other children of Martin Jones were found. These DNA matches did not share any DNA with Dan Smith and only shared with the test-taker through the Jones line. Unfortunately, however, because of the large group of Jones matches that share Smith DNA, these matches also appeared in the same cluster and subcluster as the rest of the Jones/Smith matches. This made using the network graph an inefficient way to complete the research.
My Homemade Network Graph
To overcome the complication, I decided to go to an old-school method of grouping matches: just using the Ancestry shared matches system. I focused only on shared matches of the three independent Jones matches. I decided to make a homemade network graph, which is nowhere near as beautiful as what Gephi puts out, but it was enough to help me get a handle on the matches.
- I started with the highest Jones match. I then only wrote down the connections between Jones Match 1 and with DNA matches I had not identified yet. Any identified matches in the shared match list were part of the Smith/Jones multiple relationships, and I did not want them in my analysis.
- I then began looking at any trees that were attached to these unidentified matches to see if I could find quick connections. I found that Match 2 descended from Frances Thompson’s father. Frances Thompson was the wife of Martin Jones. Therefore Match 2 would lead me to Thompson DNA, and not the Jones DNA I was looking for.
- As I wasn’t able to make connections based simply on the trees of the other matches, I started looking at their shared matches too. Match 1 and Match 6 both shared DNA with Match 2, the identified Thompson match. This showed me these were Thompson matches and not pertinent to my objective.
- When I looked at the shared matches of Match 3 and Match 5, I found that both matches shared DNA with some independent Smith matches that I had identified in my previous project. This made me realize that Match 3 and Match 5 were probably Smith/Jones matches, and would confuse my results.
- This left me with Match 4, which I thought might be a Jones match. Working on their tree, I believe that Match 4 is another direct descendant of Martin Jones and Frances Thompson, but I am waiting on a response from Match 4 to be sure I built the tree correctly as there were some gaps in the records.
- I then began to look at Match 4’s shared matches to see what else I could find.
- Looking at the trees of these matches revealed the other two independent Jones matches that were discussed earlier in this project. The rest of the matches did not share DNA with the independent Smiths or Thompsons, and therefore I thought might be matches with Jones DNA.
- I then looked at the shared matches of Match 9 and 11, as they were confirmed direct descendants of Martin Jones, and by the end, I had a pretty good group of matches to research as I looked for Martin’s parents.
The Jones project is an ongoing project that does not have a solution currently. However, this process allowed me to overcome the complications that came from multiple relationships in the family tree. Multiple relationships can definitely slow a project down, but remember, it is just a bump in the road and there is a way to work your way through the DNA mess! I learned a lot through this project and this process, but it is only one example of how to deal with this problem. Hopefully, my homemade network will eventually lead to the answer of who Martin’s parents were!
Diahan Southard offers an online course about dealing with endogamy, pedigree collapse, and multiple relationships. Diahan has a wonderful way of teaching about DNA that helps you gain confidence! The course is now enrolling for a session from October 17 – November 7, 2022, for $129 USD. Learn more and register here: Start Untangling Your Family Tree | Endogamy & DNA Course (This is an affiliate link. If you register, we receive a small commission, but it doesn’t change the price of your registration).
To learn how to create network graphs like the ones in this article, join our online course, Research Like a Pro with DNA. In this course, we take you step by step through organizing and analyzing your matches and applying DNA evidence to focused research questions.