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Many people misunderstand triangulation in genetic genealogy research. This extends to the question of whether you can use close matches to unravel ancestral connections.
Let the confusion persist no longer.
Understanding the Essence of DNA Triangulation
Before we delve into the role of close matches, let's first grasp the fundamental concept of DNA triangulation. Triangulation occurs when three or more individuals share the exact same DNA segment, indicating a common ancestor.
It goes beyond mere DNA sharing; it's about identifying specific shared segments.
I explain multiple scenarios with diagrams to enhance your understanding of DNA Triangulation in this video.
Exploring Scenarios: Close Matches and Triangulation
Case 1: Ancestral Lineage - A and B Match C
In this scenario, individual A is the father of B, and both A and B match individual C on the same DNA segment. At a glance, this might seem like triangulation.
However, since B inherited the DNA from A, it falls short of true triangulation.
Instead, it is a comparison between A and C, excluding B from the equation.
Case 2: Sibling Connections - A and B Match C
Let's turn our attention to siblings, where A and B share a parent and both match individual C. Although A and B match each other due to their sibling relationship, it doesn't meet the criteria for optimal triangulation.
Comparing C to the parent of A and B duplicates the information, diminishing the value of triangulation.
Case 3: Second Cousins - A and B Match C
In this scenario, A and B are second cousins who share a great-grandparent, and both match individual C on the same DNA segment.
While it may initially appear as triangulation, it still falls short. Like siblings, the comparison primarily revolves around C and the shared ancestor of A and B, lacking the desired depth.
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The Essence of Good Triangulation
Now, let's explore what genuine triangulation entails. Consider a scenario where three individuals, A, B, and C, share a DNA segment, but their precise relationship remains unknown.
This serves as a prime example of good triangulation. Extensive research would reveal that all three individuals trace their lineage back to a single most recent common ancestor.
Scenario 1: Unknown Relationships - A, B, and C
Imagine three individuals, A, B, and C, who share a DNA segment but lack knowledge of their specific relationships.
This exemplifies good triangulation since all three can be traced back to a common ancestor. The varying number of generations between them showcases the depth of their ancestral connections.
Scenario 2: Known Relationships - A, B, and C
Let's now consider a situation where the relationship between A and B is known, and both triangulate with individual C. Does this automatically mean that C is descended from A and B's most recent common ancestor?
Not necessarily. However, this still qualifies as good triangulation since all three individuals have a direct link to a common ancestor.
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Utilizing Close Relationships in Triangulation
When it comes to close relationships like siblings, nephews, or half-siblings, the effectiveness of triangulation diminishes. While they can be determined through shared DNA, triangulation is often unnecessary due to the presence of other identifying information.
For optimal results, it is advisable to focus on second, third, or fourth cousins and unknown relationships.
The utilization of close matches for DNA triangulation requires careful consideration. Good triangulation involves identifying shared segments among individuals with diverse ancestral connections.
Close matches, such as siblings or known relationships, can still contribute to triangulation but are often overshadowed by the availability of other information. To make the most of your genetic genealogy research, exploring relationships beyond immediate family members is recommended.
So, embark on your triangulation journey and unlock the secrets of your genetic heritage!
For more DNA Tutorials:
Check out these blog posts.
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