3 Reasons to Test mtDNA


Why should you take an mtDNA test for genetic genealogy? It’s the least-used of the testing types, but here are scenarios when it can be very helpful.

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DNA testing is becoming more and more integrated into our traditional genealogical research. Millions of people have completed some form of DNA test, and the idea that genetics can help in your genealogy is finally a commonplace notion.

However, in the wake of the widespread success of autosomal DNA testing at companies like Ancestry.com and 23andMe, the two other kinds of DNA tests are often overlooked. The Y chromosome DNA that traces a direct paternal line has gotten some attention, but the mitochondrial DNA test, or mtDNA, for direct female lines is still underutilized.

Why take an mtDNA test


Your mtDNA is directly maternally inherited, meaning that you have the same mtDNA as your mother and all of your siblings. It is the same mtDNA as your maternal grandmother, and her mother, and so on, for ten generations or more.

Unlike autosomal DNA testing, mtDNA reliably reaches back past the fourth or fifth generation in your pedigree. But unlike YDNA tests, it doesn’t tell you how closely you are related to your mtDNA matches. So it’s a test that needs to be used strategically.

Here are three scenarios when you might want to turn to mtDNA.

1. Fading mtDNA line

Let’s say you have an ailing great aunt, or you yourself are one of the last remaining carriers of your mother’s mtDNA.

Having your mtDNA tested first and foremost creates a record of your direct maternal line. Just as you would obtain a birth certificate or marriage license for your ancestor to see what other important genealogical information it might contain, having a record of your mtDNA is an important part of documenting your maternal line.

2. Female ancestor with unknown ethnicity

Let’s say you have a female ancestor whose ethnicity is unknown. Perhaps you think she is Native American or African American.

Along with your mtDNA profile, which helps you make connections with others, taking an mtDNA test gives you a haplogroup, or a deep ancestral group. There are different haplogroups for different world regions and populations. Sometimes knowing your haplogroup can help either confirm or dispel a family rumor about the heritage of a particular ancestor. Though for most it will just verify what you already know, like confirming that your maternal line is from western Europe.

3. Total brick wall

Let’s say it feels like, in 1873, aliens deposited your female ancestor in Virginia! If you have tried every other avenue to discover your ancestor’s origins, and currently your best theory of her origins revolves around extraterrestrial beings, you can try mtDNA testing.

The results of the testing will provide you with a list of individuals who may share direct maternal line ancestry with you, and therefore might be related to this mystery ancestor. However, that shared ancestor could be as recent as 1873, or as distant as dates that require the postnominal “B.C.” So, it is more or less a shot in the dark. But hey, if you don’t shoot, you will definitely miss!

In genera,l mtDNA testing should not be the first test you turn to when seeking out your ancestors. But it does have its place in your genealogical toolbox, especially as an option to test out a research theory, so don’t be afraid to pull it out once in awhile. Test your mtDNA at Family Tree DNA.

If you decide to test, I highly recommend you also purchase my inexpensive-yet-valuable Mitochondrial DNA (mtDNA) for the Genealogist guide. It explains what this kind of test may tell you, what haplogroups really tell you, and how to understand and work with your matches, which is a slightly different experience than working with autosomal matches.

Originally published at www.genealogygems.com. Updated and republished 2019.