How to Use mtDNA Haplogroup Information in Your Family History Research

Have you wondered how you can use mitochondrial DNA in your family history research? In my last post, “Mitochondrial DNA – a Blast From the Past,” I wrote about mitochondrial DNA inheritance. This post will build on that foundation and explain how you can use mtDNA haplogroup information to discern between two possible women ancestors.

You’ll remember that both men and women inherit Mitochondrial DNA (mtDNA) from their matrilineal ancestors. In other words, mtDNA passes from your mother’s, mother’s, mother’s, etc., line down to you. mtDNA is genealogically significant because of its unique inheritance pattern, and it is most effective in researching ancestors when considered along with autosomal DNA results.

Most effective steps to take to incorporate mtDNA in your research:

Take an autosomal DNA test from AncestryDNA, 23andMe, MyHeritage, Family Tree DNA, or Living DNA.

- - Remember that AncestryDNA has the most family trees associated with DNA matches results

- - - 23andMe, MyHeritage, and Family Tree DNA test results show DNA segment data, for comparison with your DNA matches.
Take a full-sequence mtDNA test from Family Tree DNA to learn the mtDNA haplogroup for you or another test taker.
- - - Another less precise option is to take a DNA test from 23andMe or Living DNA to discover an estimated mtDNA haplogroup.
    - Only compare haplogroup designations from the same testing company as there may be differences in the version of the chip used between companies.
Record the reported haplogroup in your research log.
Use autosomal DNA test results to verify the genetic connection to your parents, grandparents, great-grandparents, and so on.
- - - Look for ancestors that you share with your DNA matches.
    - Identify your most distant matrilineal line ancestor

Use this chart to remind you of DNA match family relationships and how they can verify a genetic connection to your common ancestors

5. To confirm additional generations of matrilineal ancestors, search for documentary evidence in record collections that may name the last proven ancestor’s mother.

6. To discern between two possible matrilineal ancestors, trace both women’s descendants seeking their matrilineal descendants who are living now.

- - - Use records and online family trees for hints of the descendants. Verify the parent to child connection for each descendant.

7. Hopefully, the descendants you seek have already taken a DNA test.

- - - If not, reach out to them and ask them if they have family history records or family lore about the ancestor(s) you share in common.
    - Ask if they would be willing to take an mtDNA test to verify or refute the hypothesis that you descend from the same matrilineal ancestor.

An example of how to use mtDNA haplogroup information

In the hypothetical pedigree chart below, the gray circles and squares marked are the people who inherited mtDNA from their matrilineal ancestors, “Margaret Gray” (outlined in pink) or “Sarah Gooding” (outlined in yellow). The three siblings in the center bottom had already taken mtDNA tests at FamilyTree DNA and autosomal DNA tests with Ancestry DNA. They verified the genetic connections back to “Willam Gallaher,” but were unsure if they descended from William’s first wife, Margaret Gray, or William’s second wife, Sarah Gooding. Conflicting dates in the existing records created confusion. Furthermore, a courthouse fire destroyed additional documents that may have clarified their third great-grandmother’s identity. They needed mtDNA evidence to discern which woman was their ancestor.

The siblings researched the descendants of both women. They identified five living people who could take an mtDNA test to confirm or refute their hypothesis that they descended from William Gallagher’s first wife, Margaret Gray. One proven female descendant of Margaret Gray replied to their request to connect, and two proven male descendants of Sarah Gooding replied that they were interested in learning more about their heritage.

All three of the potential test-takers agreed to take a mitochondrial DNA test at Family Tree DNA and an autosomal DNA test at AncestryDNA. The test results revealed the Haplogroup H3g1 for the two male descendants of Sarah Gooding and the Haplogroup T1a1 for the female descendant of Margaret Gray. Because the three siblings with the unknown female ancestor all showed the Haplogroup H3g1 they could identify Sarah Gooding as their ancestor, refuting the original hypothesis of Margaret Gray.

The following chart shows the inheritance pattern, color-coded by each wife.

For the original three siblings, learning the mtDNA haplogroup confirmed an ancestor and opened the door to new research to find and confirm additional matrilineal ancestors.

The following resources will deepen your understanding of how to use mtDNA in your family history research.