The ABCs of mtDNA, by Megan Smolenyak Smolenyak

When it comes to genetic genealogy (which I often refer to as genetealogy), Y-DNA is by far the most popular type of testing–and understandably so. Since Y-DNA is passed from father to son down through the generations (just like surnames) its application is fairly obvious. But over time, mitochondrial DNA (usually shortened to mtDNA) testing has been gaining in popularity.

How mtDNA Travels
Many folks regard mtDNA as the equivalent of a maternal version of Y-DNA testing and while there are some parallels, there are also some differences, and that creates a lot of confusion.

For instance, mtDNA is passed down through maternal lines, but mothers pass it on to both their sons and their daughters. The sons, however, become mtDNA dead ends and do not pass it on. This means that a brother and sister (who share the same mother) can both get tested for mtDNA, and that they both can serve as living representatives of their mother, their mother’s mother, their mother’s mother’s mother, and so on. (Think of the bottom line of a pedigree chart). But when this brother and sister pass on, her children will continue to sport the same mtDNA, while his will have his wife’s mtDNA.

Primarily a Deep Ancestry Tool
Perhaps the most important aspect of mtDNA to grasp is that it’s essentially a deep ancestry test, and is not as genealogically useful as Y-DNA. If you’re familiar with Bryan Sykes’s best-seller, “The Seven Daughters of Eve,” you may recall that the underlying premise is that 95 percent of people of European origin can trace their maternal roots to one of seven women who lived in Europe approximately 10,000-45,000 years ago.

I, for example, am from haplogroup H (haplogroups might be thought of as branches of the world’s family tree–in this case, the world’s maternal family tree), which Sykes dubbed Helena. Her descendants were the most successful in reproducing. Consequently, roughly 30-40% of those of European origin are also H. And this, in turns, means that I have millions of maternal cousins. That’s not tremendously helpful to know when it comes to tackling my family tree.

Are You My Cousin?
Unfortunately, a lot of genetealogy newbies fail to understand this, so once they get their results, they tend to play the matchmaking game. By this, I mean that they e-mail everyone who matches their mtDNA, share the usual name/place/date details of their direct maternal line back to their earliest-known ancestor, and then cross their fingers hoping for someone to report back having found some overlap. But because it’s such a massive fishing expedition, this hardly ever happens. (I know of one success story, and in my mind, this person hit the mtDNA lotto!)

Given its limited utility, why would folks even be interested in taking mtDNA tests? One reason is simple curiosity. A lot of people are genuinely interested in knowing about their deep ancestry. So if you want to know roughly when and how your direct maternal line migrated out of Africa, you might take this test to find out. For most folks, this is all they will learn, but for many, it’s sufficient.

Three Exceptions and . . .
Having just said that mtDNA tests are not very helpful for genealogical purposes, I’d like to point out a few important exceptions:

  • First, you might be lucky enough to have rare mtDNA (taking the tree analogy a little further, you could think of this as coming from a branch or even a twig with very few leaves on it). This was true of Ann Turner, who co-authored “Trace Your Roots with DNA: Using Genetic Tests to Explore Your Family Tree” with me. Some people like Ann have very few, if any, mtDNA matches. Even though she is also in haplogroup H, the most common European one, she has a couple of additional mutations that reduce the number of exact matches all the way down to one. In cases like this, it makes sense to play the matchmaking game and compare notes.
  • Second, you might be dealing with degraded remains, as is often the case with history mysteries. For instance, I recently worked on a BBC show to try to identify the two skeletons found in the turret of the USS Monitor a few years ago. In cases like this, scientists would love to use Y-DNA, but it’s too fragile and doesn’t survive. MtDNA, by contrast, is plentiful, so it is more resilient. It’s not as precise, but it’s usually all scientists have to work with. So in this case, I took the maternal lines of the sailors who lost their lives in the USS Monitor, and traced them forward in time to find living maternal relatives to serve as a basis for comparison to the DNA extracted from the remains. This is also what I routinely do on my cases for the U.S. Army’s repatriation project (to help identify remains of servicemen still unaccounted for from WWII, Korea, and Southeast Asia).
  • Third, you may have a specific, maternally-oriented genealogical conundrum–and if you’re strategic about it, you just might be able to come up with a clever way to resolve it using mtDNA testing. There are a few examples on pages 69-73 of “Trace Your Roots with DNA.” (Those who are registered at Amazon can use the “search inside this book” feature to view these pages or you can click here for a detailed version of one of the examples given).

. . . A Couple of Caveats
To this list of exceptions, I now need to add a pair of qualifiers. The good news is that testing companies and avid genetealogists are working together in an attempt to refine haplogroups. For instance, when I first got my mtDNA tested several years ago, I learned that I was H. Now I can find out that I’m H1*. Returning to the tree analogy, it’s somewhat akin to learning which twig off of the H branch my maternal line comes from.

Also, mtDNA is finite. It has 16,569 base pairs, which sounds like a lot, but is nothing compared to the billions of bases found in nuclear DNA that’s used for Y-DNA tests. So it’s in the realm of the possible to test for your entire mtDNA sequence, which translates into very precise results.

The catch? Well, there are two. Once you have your sequence, you can theoretically play the matchmaking game again, but at prices currently in the $795-895 range, you probably won’t have too many to compare against until prices come down. And I need to point out that a full-sequence mtDNA test is the first genealogical one that could conceivably give away medical secrets. Some conditions are passed through maternal lines (e.g., some kinds of muscle disorders), so your results could potentially reveal more than you’d care to know. Of course, you’d have to take your results (which are well-protected) and do some fairly intensive research or consult a genetic counselor, but in the interest of full disclosure, I feel obligated to mention this possibility.

Hop in the mtDNA Pool!
If you’re new to genetic genealogy, I know this is a lot to absorb, so I’d suggest that you start with more conventional Y-DNA testing, perhaps joining a surname project. But if you’re ready to take the next step or are just plain curious, I hope this primer will help you understand just what you can and can’t learn from mtDNA testing.

Click here for a printer friendly version of this article.

Megan Smolenyak Smolenyak, co-author (with Ann Turner) of Trace Your Roots with DNA: Using Genetic Tests to Explore Your Family Tree (as well as In Search of Our Ancestors, Honoring Our Ancestors and They Came to America), can be contacted through,, and

Upcoming Events Where Megan Will Be Speaking
— Joint Genealogical Speakers Guild and International Society of Family History Writers and Editors luncheon at the FGS conference
(September 2, 2006 – Boston, MA)
— David Ackerman Descendants 1662
(October 21, 2006 – Ramapo, NJ)
— 2006 Genealogy Conference and Cruise (hosted by Wholly Genes Software)
(November 11-18, 2006 – Mexican Riviera)

Details and links to upcoming events

15 thoughts on “The ABCs of mtDNA, by Megan Smolenyak Smolenyak

  1. Very informative. I made a copy to share with one of my non genealogy friends who had some time ago given me an article from a newspaper talking about DNA testing.

  2. Good article. However Megan missed a great opportunity to promote the Natioinal Geographic’s non-profit research project, The Genographic Project at where they are mapping ancient DNA. The cost is about $100 and after getting my results, I was able to submit them to Family Tree DNA for free. Their computer searches for matches and emails you with new matches.

  3. Hey! There are those of us who look into genealogy because we feel the need to find our roots. Our REAL roots. I’m adopted and have often searched strangers faces trying to identify “my nose.” I saw the cover of the National Geographic back in 1979 of the Iraqi woman with the haunting eyes and very high cheek bones. I immediately felt a kinship. Here it is 2006 and I run across the follow-up article on the same woman that reveals her subsequent life. That spurred me on to do what I had previously thought was pointless…have my mtDNA examined. The National Geographic Xenographic Study performed the test for me for a mere $100. They also matched my results with others participating in the program. I received a fairly detailed analysis and even was contacted by another woman researching her family history. We did not have any match at the time because I knew nothing of my own history.
    The big news is that my DNA study revealed my maternal ancestors originated from the same area of the world as the Iraqi woman on the cover of the National Geographic. I had finally found “my nose” and my eyes and my cheekbones!
    Just wanted to let you know the study could be done for far less than the amount you quoted and sent to other sites for comparison.
    Thanks for all you do! Janice

  4. An excellent and informative article, especially considering the dificulty in finding any DNA information that is not so complex as to be nearly useless for the average genealogist. I wish Megan would add just one more paragraph explaining the adquacy of mtDNA tests that offer results such as claimed by Opra Winfrey, i.e. percent of white, percent of American Indian, percent of black, etc.

  5. Hi Milton, Carolyn, Janice and Harry,

    Thanks very much for your comments. It sounds as if it might be a good idea for me to write future articles on National Geographic’s Genographic project, as well as BioGeographical (aka AncestryByDNA) tests (the one you’re referring to, Harry). I know from all the speaking I do that these are two other areas that confuse folks — and as with mtDNA, there are nuances that are often glossed over. So I’ll put them on my to-do list.

    Also, just to clarify, while I discussed the latest full-sequence mtDNA tests above, standard mtDNA tests generally run around $100-200.

    Thanks again for your input.

    Take care,

  6. Would apreciate more information about dna mtdna and y dna.

    It has been said within my mother’s Randolph family tree that we connected with Thomas Jefferson’s Randolph mother’s line who came over from the northern American states from England, etc. However, from learning further it was noted that Churchill wrote extensive books about the Randolph’s and their connection to King of England, etc. Have figured that the dna would go back and confirm these “passed down families word from word situations.” Thanks, for the help. Eleanora Randolph-Lyons Alexander & families thereof.

  7. I am fascinated by what can be learned about the human race via DNA and mtDNA testing. I have thought of having my own done; however I am held back by thinking that my results could fall into the hands of people/organizations that could use them in ways I probably can’t even imagine. I never have seen this concern pointed out in any writings, ever. Anyone besides myself concerned?

  8. The Sorenson Molecular Genealogy Foundation, which is based in Salt Lake City, would be another interesting topic. They will test your DNA for free, and protect your privacy, but you have to provide a pedigree of at least four generations. Apparently I have a rare mtDNA HVR1+HVR2 combination, and the only match I’ve found is in their database…..

  9. I am printing this for my son who is interested in finding if we have indian ancesters. What makes it hard is my dads mother is suppose to be of indian blood, and the way I read it,
    it would stop in my dad and not go to me, is that right?
    Betty Swale

  10. I had my MtDNA tested because I am the only living person with my gr-grandmother’s MtDNA. When I die there will be none left. While it may not be particularly useful now, perhaps future developments will make it useful.

  11. As near as i can figure, this is the only DNA test that can be useful for me — short of exhuming caskets to see if bodies remain. My father, his brothers, and his sister have been dead for at least 16 years. The last one to die was cremated and his ashes were scattered. The two who had children only had girls, and their father was an only child. Like Al, i will have my MtDNA tested just in case future developments make it more useful.

  12. I had the same concerns about privacy issues as Susan Spurgeon, 9 Aug. 2006, however, my curiosity about my mtDNA won out and I had the HVR1 test. This really didn’t go far enough, so now I am waiting on results from the HVR2 and HVR3 testing. Governments/people/organizations desiring to get this information about individuals will find a way to do it, in one manner or another.

  13. I was given this as a Xmas present and have suffered nothing but heartache. I mailed in my test and created my family tree at, but I discovered several problems that could not be solved on the genebase website. There is no online help forum or manual. There is no number for technical support. A woman in sales named Victoria just hung up on me. She told me that tech support only exists through email and I cannot speak to anyone. I have exchanged at least 5 emails with “tech support” and none are helpful or even reflect that they understand the problem. I requested a refund and was told that my purchase only covered the dna testing and that the genebase website is a free service. And since my sample had been mailed (it has not yet been tested), I did not qualify for a refund! They would only be able to “deactivate” my genebase account. Then she hung up on me. I vaguely remember raising my voice in horror and consternation, but nothing that would justify being hung up on. Wow. What good is dna testing if you can’t link it up to your family tree to see the connections? I’ve been struggling with this since xmas week. Save yourself headaches and heartbreak and research before you buy. Anybody have any good experiences elsewhere?

  14. I am in a hurry since my Dad is 82 yrs old. I want his dna tested as we are supposed to have Native American (Cherokee)blood through his mom but of course, can’t prove it. Since the testing is so expensive and so many different ones to choose, could you please advise which type is the best type to have run. The reason I have delayed is due to the expensive costs of all the different types and I don’t want to pay for one test after another because I chose the wrong type. After reading all the types of dna testing available and since this definitely is NOT my field of expertise, I really would appreciate the help. And, my last, most important question- Does the dna test really tell you Native American dna exists if it was only off of one branch of the tree? I was going to try the testing. Any comments?
    Curious and can’t wait much longer. Thank you for your time and help!!

  15. Wonderful collections. You have done a great job. Your article is very informative and interesting. I will never miss your article related to science.


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