Genetic Networks, Part 3: How to Find Them

In the first two blog posts, I defined genetic networks (Part 1) and discussed the inclusion and exclusion criteria for matches within the network (Part 2). Now, I describe how to easily find genetic networks within your list of autosomal DNA matches. As in prior posts, I label these matches as A (test taker), B (match being viewed), and C (matches that both A and B also match).

Within our list of DNA matches, we have many different genetic networks. Each ancestor may be represented by several genetic networks depending on the number of matches we have and the segment or group of segments they passed down to their descendants. Many methods exist to find genetic networks, and I group them into three types – 1) DNA testing website filters, 2) strategic tree triangulation, and 3) automated tools. Each type has their associated advantages and disadvantages.

DNA Testing Website Filters
When reviewing a match (B) for a DNA test taker (A), the most frequently used DNA testing websites provide a filter or a list of shared DNA matches (C). While testing websites use dissimilar terminology (see list below) or present shared matches differently on their respective websites (see image below), these filters are generally easy to use. However, as discussed in the previous post, it’s important not to accept all listed shared matches (C) as true members of the same genetic network shared by “A” and “B”. While the number of misclassified matches is small, you should verify their inclusion by doing traditional genealogy and/or “viewed match switching”.[1]

• Ancestry: Shared Matches[2]
• FamilyTreeDNA: In Common with Matches
• Gedmatch: People who match both, or 1 of 2 kits
• LivingDNA: In Common
• MyHeritage: Shared DNA Matches
• 23andMe: Relatives In Common

Strategic Tree Triangulation
If DNA testing website filters are the means to visualize genetic networks, then strategic tree triangulation is how genetic networks are tactically utilized. Tree triangulation is “the process of reviewing the pedigree charts of clusters of shared matches/in common with matches in order to identify a common ancestor or ancestral couple”.[3]

Therefore, strategic tree triangulation is the process of using DNA matches selectively to discover the shared matches (i.e., genetic networks) associated with an unknown ancestor or ancestral couple and then analyzing the pedigree charts associated with those matches (see image below). As such, strategic tree triangulation requires that you:

• Find a match (B) that descends through another child line of the unknown ancestor other than your tester’s direct line (A) such that
• The “B” match’s only common ancestor with the tester (A) should be the unknown ancestor or ancestral couple.
• Then perform tree triangulation within the resulting list of shared matches between “A” and “B”.

Strategic tree triangulation is how I’ve broken down many brick walls, and I principally use two methods to strategically triangulate shared matches’ trees to discover a previously unknown ancestor: EGGOS Search Strategy and Ancestry ThruLines®.

EGGOS is an acronym for Earliest Generation Group of Siblings, and I previously presented this strategy in an earlier blog post and YouTube Learning Module. The EGGOS Search Strategy assumes you are looking for one ancestor or ancestral couple in a particular generation (generation four in the above image). To find relevant genetic networks for these ancestors, you look for a DNA match (B) among your list of matches who descends through a different child line other than your own ancestral line (A). If possible, the different child line should be at the generation just below the unknown ancestor (generation 3 in the above image). In other words, the earliest generation (generation 3) rather than a more recent generation (generation 2 in the above image). Ideally, the “B” match should only share the unknown common ancestor as the most recent common ancestor. If the match shares a more recent common ancestor, then any identified genetic networks may represent any or all common ancestors shared between “A” and “B”.

The EGGOS Search Strategy works great if you are aware of a sibling to your ancestor whose parent or parents are unknown. However, if you’re not aware of any siblings other than your own or there were none, then you might have to use a more recent generation, but of course any identified genetic networks may include more common ancestors than the unknown ancestor. If you must utilize a more recent generation, the figure below shows how the genetic network may be expanded to represent the common ancestors at generation four (in yellow) as well as those at generation three (in red). The yellow and red ancestors represent an expanded genetic network, and you should be conscious of this as you evaluate the matches within the network.

EGGOS also assumes you previously identified the relevant “B” match among your matches. If you have not or cannot, Ancestry’s ThruLines® might be able to help. ThruLines® are suggestions Ancestry makes by reviewing your DNA matches’ family trees and indicating how your matches might be related to you. An important caution here is that they are suggestions. You need to do the work to make sure the espoused genetic path indicated by Ancestry is how you’re actually related as previously discussed in the prior blog post.

Because Ancestry uses other people’s trees to make their suggestions for ThruLines®, how you are related to the match may not be accurate. People make mistakes in their trees. So, review the shared matches (C) with the ThruLines® match (B) to verify that most “C” matches share the same common ancestor or ancestral lines as proposed by ThruLines®. If it looks like a good suggested match, then you have a genetic network that you can use to help you discover the identity of the unknown ancestor(s), which is discussed in Part 5 of this blog series.

Automated Tools
Given the number of DNA matches we often have, it can be difficult to identify genetic networks even with DNA testing website filters, ThruLines®, and other search strategies like EGGOS. This is why several companies and individuals have developed automated tools to help us. The tools perform autoclustering, which automatically goes through your list of DNA matches and organizes them into genetic networks or clusters. The image below demonstrates what one of these tools, MyHeritage’s AutoClusters, looks like (match names blurred for privacy).

In interest of both time and space, I will not go into detail for how to use each tool. Rather, I will list them as a resource should you consider this route. Interested readers are encouraged to visit the respective websites to learn more about them and learn how to use them. Most companies offering these tools provide good instructional content.

Company	Tool	Cost
DNAGedcom	Collins Leeds Method	$5 per month or $50 annually
GEDmatch	Clusters With AutoTree, Closest to Single Kit Version Find Common Ancestors (MRCA) from DNA Matches Find Surname Matches from DNA Matches	Tier 1 membership ($15 per month or $10 per month with autorenewal)
Genetic Affairs	AutoCluster AutoFastCluster AutoSegment AutoTree AutoKinship AutoPedigree hybrid AutoSegment	Limited free trial, or $5.00 per month for advanced features
MyHeritage	AutoClusters	Free for MyHeritage kits, or $29 one-time unlock fee for uploaded DNA from other testing websites

Some tools have a limitation for the number of matches analyzed and thus clustered into genetic networks. Personally, I have not had as much success with automated tools as I have with DNA testing website filters and strategic tree triangulation.

Conclusion
Depending on the stage of your research or your genealogical research question, your methodological preference for finding genetic networks may vary. If you’re exploring your matches to identify genetic networks, then automated tools may be best. However, if you are working on a particular line or have a specific research question, then a more strategic approach may be more useful, such as testing website filters, ThruLines®, or EGGOS Search Strategy.

In Part 4 of the blog series, I describe how to efficiently review the family trees for your shared matches within your genetic research. I also discuss how genetic networks should be used in your research.

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Sources
[1] Viewed match switching entails swapping out the “B” match being viewed with the “C” match in question and observing how the membership of the genetic network changes (i.e., other “C” matches). See Part 2 of this blog post series to learn more about this process.
[2] Ancestry now offers Enhanced Shared Matches with its Pro Tools subscription add-on, which permits users to view how much DNA your viewed match shares the other shared matches. Enhanced Shared Matches is discussed in Part 5 of this Genetic Network series. See also, Ancestry Pro Tools’ Enhanced Shared Matches: Is It Worth $10 per Month?
[3] International Society of Genetic Genealogy (ISOGG) Wiki, (2023, June 4). Triangulation. Accessed 18 June 2024 at https://isogg.org/wiki/Triangulation.

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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.

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