Help:Relationship Finder for Genetic Genealogy
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WikiTree's Relationship Finder has unique features for using autosomal DNA tests to confirm relationships.
See Relationship Finder for basic information about the tool.
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Explore More: Browse All Common Ancestors
WikiTree's Relationship Finder finds the first common ancestor shared by the two people.
As a genetic genealogist, you want to know more than the first common ancestor. If you share a segment of autosomal DNA with someone else, it may have come from your most recent common ancestor, but it may have also come from one or more other ancestors you share in common.
If the Relationship Finder finds more than one common ancestor you can explore them using the pull-down menu labeled Explore more.
Ignore ancestors beyond 15 generations
Unlike with Y-chromosome and mitochondrial DNA, no more than 10 or 15 generations, at most, are likely to be relevant for autosomal DNA tests.
If you have a relationship with someone that's more than 15 generations back, it's almost certainly not the relationship that has given you a significant shared segment of autosomal DNA. [1] If you are identified as a match with another person and yet the only common ancestor you're finding with that person is older than 10 generations back, it could very well be because other more recent relationships haven't been identified on WikiTree yet.
The selection box for multiple common ancestors shows how far back a common ancestor is. For example, "Joe Schmoe at gen. 10/12" indicates that Joe Schmoe is ten generations from the first person and 12 generations from the second person.
Explore "pedigree collapse"
To further complicate your analysis, you may find that a person is related to the common ancestor in multiple ways. This is increasingly common with distant ancestors, and another reason to dismiss matches beyond 10 or 15 generations.
To explore the multiple connections between a person and their ancestor, click the link that says "X is descended from Y in more than one way" and then click to view the alternate paths in the "explore more" section of the new page.
Encourage your matches to add their family
The greatest limitation of the Relationship Finder, of course, is that it's only as good as the relationships on WikiTree. The web of relationships on WikiTree will never be perfectly complete and correct, but it gets better every day through member contributions.
Encourage your matches to help build our shared tree. See DNA Matches for ways WikiTree makes it easier to work with matches.
Advanced Filter: Limit to Ancestors Shared by Other Matches
If the Relationship Finder finds more than one common ancestor, you can filter the common ancestors by one or more additional people.
An input box will appear below the selection box for browsing your multiple common ancestors. It's labeled "Advanced filter." This enables you to limit the results to common ancestors who are also shared by one or more additional people.
If you enter more than one WikiTree IDs, separate them with commas.
Limit to paternal or maternal side
If you know a match is on your father's or mother's side you can enter your father's or mother's WikiTree ID in the advanced filter. That will immediately limit the common ancestors to those on your paternal or maternal side.
You can also restart the Relationship Finder using your father's or mother's ID instead of your own.
Triangulation
This filter is designed to facilitate "triangulation." If you share a segment of autosomal DNA with two or more other people who also match each other on that segment, that's a big clue in discovering which ancestor it came from.
For example, the Relationship Finder for Lianne Lavoie (Lavoie-74) and Roland Arsenault (Arsenault-64) finds over 100 common ancestors. If a third member, Annette Cormier (Cormier-577), also matches them on the same segment of DNA, they can filter by Cormer-577 and it limits it considerably. If we add a fourth or fifth person we might isolate exactly where the DNA came from.
Experiment with the order in which you add additional IDs
If you're limiting the display to ancestors who are also shared by a third, fourth, or fifth person, you may need to rearrange and experiment with the order in which you enter them.
The two you start with should be the most distantly-related. For example, if you know that one of your matches is a third cousin and the other is a fourth cousin, start with you and your fourth cousin. Then limit the display by entering your third cousin.
When entering a third, fourth or fifth person, it's best to enter them one at a time. That is, instead of entering all three IDs in the filter, add the third, then the fourth, then the fifth. If you enter them all at once you will only see ancestors that are shared by all five people. If only three or four of them have common ancestors they won't be found.
You can play with the order as much as you want. Just be patient while the connections load. It may take a minute or two, depending on the number of common ancestors.
- ↑ DNA testing companies won't identify two people as a match based on a very small shared segment. Small segments may be coincidental instead of inherited from a common ancestor. For related information see the ISOGG explanations for "Identical by state" (IBS) vs. identical by descent" (IBD).
Blaine Bettinger points out that "although FTDNA will only identify two people as a match if they share at least one segment of 7.5 cM or longer, it will report shared segments as small as 1 cM once the initial match is found."
This page was last modified 15:27, 9 October 2021. This page has been accessed 14,649 times.