Proving Your Tree with DNA?

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Image generated by Nanobnana 2 May 2026

If you have tested your DNA for genealogy, you are either excited by all the new information coming your way, or hopelessly bewildered—or somewhere in-between, like many of us. If you and close relatives have tested at least you can easily prove the beginning of your DNA tree, which is YOU and your biological relatives. This DNA tree may or may not be the same as the research that you have labored over for many years, hunting for official records, context and other evidence of the lives of your relatives and ancestors. 

If you have been "doing genealogy" for a while you know the final step: writing it up. But how to do that with DNA evidence? How do you explain all those numbers so that they mean something, much less PROVE your tree? And how can I say it is "easy?" I recently found the answer in Legacy Family Tree Webinars by Karen Stanbary, CG®, CGG® in a series called DNA in Action; 2 of 6 which are available. I plan to watch all of them. Very clear, logical, and irresistibly simple.

I started with the easiest proof, between two close relatives who have DNA tested. My research  begins with the question: Who is the biological father of Valorie Cowan Zimmerman?

If Valorie is the biological daughter of  of Ted Cowan, they should share autosomal DNA (atDNA) consistent with the typical amount for parent and child. Statistically parents and children share 3485cM with a standard deviation of 114cM, according to The Shared cM Project [1].

Valorie and and Ted Cowan share 3587.8cM [2]; they are in a parent-child relationship according to the Shared DNA Project, which says that relationship is 100 percent certain. 

DNA does not show which which person is the child.

 Valorie has a birth certificate [3] which shows her to be the daughter of Ted Cowan and Lola McBee Cowan. Both atDNA and direct documentary evidence prove that Valorie is the biological daughter of Ted Cowan.

In a similar fashion, I can prove that my sister, who also tested, is my biological sister. 

However, proving that Lola McBee is my biological mother will be more complicated, because I must infer her DNA relationship through matches between me, my sister, and our cousins and one of her brothers. In the same way I can prove my relationship to our grandparents. Each step beyond parent-child involves more logical steps to prove the case.

We will be discussing this in the near future:


istockphotos.com Free
11 May 2026, 1-2 pm PT:  SKCGS Genetic Genealogy/DNA Interest Group meeting. Topic: Proving your Family Tree with DNA Evidence. See DNA in Action 1 of 6: Proving Your Pedigree with DNA: https://familytreewebinars.com/webinar/dna-in-action-1-of-6-proving-your-pedigree-with-dna. We are genealogists who use DNA data as part of their research. Join the free email group for meeting notices and discussion: https://skcgs.groups.io/g/Genetic-Genealogy. Register for the Zoom link on SKCGS.org.g


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1.  The Shared cM Project [1] 4.0 tool v4 <https://dnapainter.com/tools/sharedcmv4>.: accessed 2 May 2026.

2. GedMatch "One to Many" tool: of Ted Cowan, kit :M186808  Gedmatch <https://app.gedmatch.com/v_compare1.php> : accessed : 2 May 2026.

3. Birth Certificate for Valorie Anne Cowan, DETAILS HELD PRIVATELY.

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