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Genetic Distance

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  • Genetic Distance

    Hi everyone,
    I searched the thread and read several posts about genetic distance but I want to be sure I understand it.

    I'm female and did the Full Sequence mtDNA test. When I look at the matches selecting the HVR1, HVR2, Coding Region option I have a total of 138 matches and 25 are a genetic distance of 0. If I understand genetic distance, these people have a 50% chance of sharing a common maternal ancestor within 5 generations. Have I got this right?

    When I look at the matches selecting the HVR1, HVR2 option I have 990 matches. So far I haven't found anyone that has a tree with whom I share a common ancestor.


  • #2
    Yes, FTDNA says that in the chart on the Learning Center page for Maternal Lineage tests. It also says 95% Confidence Interval of 22 generations (550 years) for the mtFullSequence test.

    But, most will agree that those are optimistic estimates. Also, mtDNA is best used not for "fishing," as Family Finder or Y-DNA tests are used, but rather for a specific genealogical problem, such as when you believe two people may be descended from a common maternal line ancestor. There is a video on YouTube featuring Bill Hurst, the project manager for the mtDNA K haplogroup, illustrating such a case.

    There have been people who have found relatives using mtDNA testing, so it's not unheard of, just not usually as successful as the other types for randomly finding a relative through mtDNA matching.

    Otherwise, you can learn things from your mtDNA testing, which may help with genealogy. Roberta Estes has a good article on mtDNA testing at FTDNA, "Mitochondrial DNA – Your Mom’s Story," which you might like to read. She describes all the aspects of the mtDNA results in your FTDNA account. She also has an article about genetic distance, both for Y and mtDNA, "Concepts – Genetic Distance."

    Sometimes, as with any DNA testing for genealogy, it can be a waiting game. I have 19 matches at the mtDNA Full Sequence level, but none of them match at genetic distance of 0. None are in the region of my earliest direct maternal line ancestor, either. And so I wait (since 2013)!
    Last edited by KATM; 4 September 2018, 04:09 PM. Reason: added more


    • #3
      As far as I'm aware, Nei's genetic distance is quite old compared to FST. However, I have recently read more papers that utilized Nei's genetic distance alongside with FST. As I'm not very familiar with Nei, what are some advantages it has over FST?

      Does Nei's genetic distance suffer from ascertainment bias?


      • #4
        From the FMS test I have 12 matches 9 of which are at a zero distance from me, then a 1, 2, and 3 distance. All have done the FF test, but one. That one (a zero distance match) I have been able to contact and we've worked out no recent relationship. All the others are not showing any FF relationship to me. So our common ancestress is quite a distance away. Personally, I think that the mtDNA test is good for deciding if someone who is a possible relation down the mother's line is actually a linked to you. Other wise it is really just a hit or miss testing.