In the previous blog posts, I defined genetic networks (Part 1), discussed the inclusion and exclusion criteria for matches within the network (Part 2), and described how to find them (Part 3). Now, I demonstrate how to efficiently review the family trees for the shared matches within a genetic network to discover your unknown ancestors. As in prior posts, I label these genetic network member matches as A (test taker), B (match being viewed), and C (matches both A and B also match).
We begin with the assumption that you have identified a genetic network of shared matches (C) associated with an unknown ancestor or ancestral couple by strategically selecting a match (B) who only shares the unknown common ancestor of interest with the test taker (A). The next task involves analyzing the pedigree charts associated with the shared matches (C) to discover potential individuals to research as the unknown ancestor using a process I call “Forest Management”.
Forest Management: Reviewing Your Matches’ Family Trees
Because not all shared matches (C) have family trees, I follow a very specific method for triangulating their family trees in search of possible candidates for the unknown ancestor or ancestral couple. I call it Forest Management, which is a three-step process of pruning, fertilizing, and harvesting genealogical information from your shared matches’ family trees. I’ve created a companion YouTube Learning Module to accompany the Forest Management method.
Pruning
With pruning, you quickly review in rapid succession all the family trees of the shared matches (C). In this gestalt pattern recognition process, I take note of frequently occurring surnames and geographies within the “C” matches’ lines. I take mental notes because I do this task quickly to gain an immediate overview of all the trees, but you could also take physical notes. Because the pruning process is rather quick, it also helps you become familiar with the matches in the network, which helps later tree triangulation processes.
The pruning process is as much about identifying possibly relevant branches of a match’s tree as about identifying irrelevant branches, too (i.e., pruning). For example, if your unknown ancestor is likely Irish, then you can probably safely ignore a match’s German lines.
If you’re reviewing “C” matches on Ancestry, I recommend using the map at the bottom of the page when reviewing a match. The map feature is titled, “Ancestor Birth Locations”, and it’s best to select just the match’s tree not both trees when using it. This can help you find relevant birth locations of the match’s ancestors to correlate with your mystery ancestor’s possible residences. The image below demonstrates how Ancestry highlights these locations using clickable pins providing the name of the match’s ancestor who was born in this location.
Fertilizing
In the prior pruning phase, I reviewed all shared matches with family trees. So, in the fertilizing phase, I concentrate on those shared matches (C) that have incomplete trees, unlinked trees, and no trees. This phase is perhaps the most labor intensive as you try to build out the family trees of these matches to discover potential candidates to research for your mystery ancestor. Fertilizing includes using traditional genealogy to build out incomplete trees as well as contacting the matches hoping they share some of their family tree information so I can construct a family tree when one did not exist.
Ancestry’s ThruLines® and Common Ancestor hints may help with fertilization, but they should be vetted to ensure accuracy. Ancestry’s Pro Tools’ Enhanced Shared Matches can be helpful, too, and this feature is discussed in Part 5 of this series. You can also look for your matches on other testing websites as many of us use the same names or user IDs for our DNA kits found elsewhere, which is discussed in Part 6 of this series. Family trees might be posted on one website but not others.
It may not be possible or even necessary to build out the family trees for every one of the shared matches in the genetic network that do not have trees. You only need to find enough of a pattern among the other shared matches to take the research from DNA analysis to traditional record searches. But if you have the time and patience, it’s best to fertilize as many trees as possible.
Harvesting
Once all or a majority of the shared match’s family trees (C) have been pruned and fertilized, I then begin to methodically harvest genealogical information from the shared matches’ family trees. It’s important to note that mistakes may be present in your matches’ trees or the trees you constructed on their behalf. Be mindful of this as you begin to harvest information especially when you observe that a match’s tree doesn’t quite fit the DNA.
During the harvesting phase, I take detailed notes for each match identifying surname and geographic patterns discovered in the prior pruning and harvesting phases. Often, I find that the genetic networks contain smaller clusters of more closely related matches where you can observe how a particular chromosome segment was passed down a particular line to more recent generations. You might see a group of siblings or parent and child who have tested. However, the best situation is to find a group of matches who are first or second cousins to one another that can help you isolate one of their ancestral lines on which to focus your research. For example, you might find two matches share a great grandparent, which helps you narrow down your research efforts to this one line. You can essentially ignore these matches’ other lines when trying to determine how they fit into your tree.
When I’m working on genetic networks associated with unknown 18th or 19th century ancestors, I often find several clusters of shared matches for which I am unable to determine how they connect to one another let alone to me. These so-called unlinked family clusters[1] provide great opportunities for documentary research but also an increased challenge for determining how they all come together. Common geography can help focus the research, while at other times, you just have to be patient for other matches or record groups to become available to help you put the pieces together.
As potential candidate lines are discovered, I transition from DNA analysis to documentary research in a process I call Genealogy Ping Pong. It’s an iterative process of using DNA to find individuals to research using traditional records like census and birth/marriage/death records and then coming back to DNA to confirm observed patterns. Like the game of ping pong, the volley between DNA and documentary evidence continues until you can construct a proof argument for the identity of the mystery ancestor. This process is elaborated on more fully in Part 7 of this series on genetic networks, which is forthcoming Oct. 21.
Two Hurdles: Analyzing Your Matches’ Family Trees
Genetic genealogist Blaine Bettinger notes that members of the genetic network should clear “Two Hurdles” when using them as evidence: matches should be valid and share the same segment.[2] In Part 2 of this series, I described how to ensure that shared matches (C) are true members of the genetic network with the tester (A) and the viewed match (B). Validity is achieved using traditional genealogy research to confirm the ancestral path between the “C” match and the potential common ancestor of “A” and “B”. Your shared matches’ family trees, whether provided by the match or constructed by you, is how validity is achieved.
Second, Bettinger recommends that a triangulated segment between “A”, “B”, and “C” be identified. That is, through a chromosome browser, it should be demonstrated that all matches share the same segment on a chromosome. Segment triangulation is not easy to accomplish as some testing websites, such as Ancestry, do not permit its users to view this data directly on their site. Users must download their raw DNA data and upload it to another site, such as Gedmatch, to view it. However, FamilyTreeDNA and MyHeritage do provide a built-in chromosome browser where you can easily see the segment shared between two or more matches (see below).
It is the opinion of other genetic genealogists that the second hurdle of segment triangulation is unnecessary. Diahan Southard reasons that the only concern genealogists should have when using a shared matches filter is that a group of shared matches (i.e., A, B, and C) share DNA.[3] However, the opinion of this author is that segment triangulation depends how you intend to use the genetic network. If the purpose is to guide your research of traditional documentary records and the genetic network is one of several pieces of evidence in a proof argument, then segment triangulation is helpful but not required. However, if the genetic network is the only piece of evidence or the primary piece of evidence, then segment triangulation is necessary. Part 6 of this series on genetic networks discusses how you might find your Ancestry matches in other databases where segment data can be visualized.
Conclusion
The tree building and tree verification process for your shared matches is perhaps the most challenging task when using genetic networks. While tedious and time consuming, it is a step that cannot be skipped. In fact, analyzing your matches’ family trees not only helps you become more familiar with your matches and your own genealogy, but it also provides greater confidence with subsequent research efforts as you progress into documentary research (see Part 7, which is forthcoming Oct. 21).
In Part 5 of the blog series, I describe how to use Ancestry Pro Tools’ Enhanced Shared Matches feature to group sub-clusters into unlinked family clusters to guide traditional record research efforts.
Sources
[1] An unlinked family cluster is a large group of matches who all descend from a single ancestor but for whom you are unable to establish your genetic relationship. See the following blog post for a more in-depth discussion of unlinked family clusters: https://myfamilypattern.com/smallmatches/.
[2] Bettinger, Blaine (2024, June 24). I know it isn’t popular, but you MUST be careful with shared matches below the 20 cM threshold (now visible with Enhanced Shared Matching at AncestryDNA). [Status update] Facebook. https://www.facebook.com/groups/geneticgenealogytipsandtechniques/posts/1961543920975965/.
[3] Southard, Diahan (2023 March 4). Shared DNA Matches – the only DNA Tool You will Ever Need. A presentation at RootsTech 2023, available at https://youtu.be/btQwRIyhuns?si=YNHgXbr5FUSGOW2r.
Acknowledgment: The image used within the header at the top of the blog post was created using Microsoft’s Copilot AI-powered assistant (DALL-E 3) and added to the title slide. AI tools were not used to generate the blog’s intellectual content or provide writing assistance. The post was authored solely by me.