Ethnicity Estimates: Myth vs. Fact

Ethnicity estimates are the most popular feature of DNA tests, yet also the most controversial.  Its popularity has inspired people who don’t really know very much about the topic to chime in with their own opinion about the estimates, which are sometimes also known as ancestry composition reports or myOrigins estimates.  Don’t worry, though, because you have come to the right place.  In this post, I’ll dispel a few of the top myths about ethnicity estimates.

Many people who have written articles for major news outlets about ethnicity estimates have never event taken a DNA test.  Many of those who have have never used their DNA results to extensively explore their family history, and almost none of them have experience with genealogy.  It’s as the old adage always goes:  When you are evaluated the accuracy of some bit of information, it is crucial to consider the source.

Myth #1  Ethnicity estimates aren’t accurate

This is the most popular myth around ethnicity estimates.   Many people claim that it’s just a clever marketing ploy by DNA testing companies in order to sell more DNA kits.  Others posit that while companies are legitimately trying to provide accurate estimates, they just can’t do it.  A smaller minority of people believe that ethnicity estimates are a small part of some intricate conspiracy, the goal of which is unclear.

Fact:  Ethnicity estimates are usually fairly accurate

While it’s true that people share 99.9% of their DNA with every other human, and we are almost completely genetically identical to each other in a grand sense, scientists are able to use the very small, statistically insignificant amount of DNA that we don’t share in order to figure out where our families might have lived.

In my extensive experience, ethnicity estimates are fairly accurate and can provide helpful insight into where our families might have lived over the past few hundred years.  They are most accurate in a general sense, meaning that if you don’t find Native American DNA in your results and instead found out that you are 100% European, there is an exceptionally high probability that you have no Native American DNA.

(Read that carefully:  You might have no Native American DNA, but this is different than having no Native American ancestors – see Myth #2)

The generally accepted rule of thumb is that these tests are almost 100% accurate at the continent level, except for percentages under 1%.  Very small percentages, or “trace” amounts of a region might be accurate, but there is also a good possibility that this is statistical noise.

Additionally, I have found that ethnicity estimates are also fairly accurate, especially with Ancestry DNA and 23 and Me, at a region-by-region level.  Most of the time when people spot an ethnicity region that doesn’t make sense to them, there is usually another explanation other than “it’s not accurate.”

Myth #2  Ethnicity estimates should match your family tree

This “myth” is the cause of the majority of incorrect information circulating about ethnicity estimates.  A person who knows a lot about their family history might take a DNA test and notice that the results don’t seem to line up with what they know about their family tree.  This leads them to draw the conclusion that the ethnicity estimate is not accurate.

Fact:  Ethnicity estimates rarely match a family tree perfectly

Aha!  You might be thinking that you have gotten me to admit something shocking about the truth behind ethnicity estimates.  It’s not so, however.  In fact, this “truth” is about how DNA is inherited.  Why is that?

We don’t inherit 100% of either of our parent’s DNA.  In fact, we only inherit 50% of our mother’s DNA and 50% of our father’s DNA.  Our parents didn’t inherit 100% of their parent’s DNA either, and just like with us, about 50% of each parent’s DNA was “left behind” and not passed down.  If you consider that the same thing happens every generation, this means that there is an incredible amount of information about your family’s full ancestry that is just lost to history.

When we take a DNA test, they are only able to perform their test on the DNA that we did inherit from our parents, grandparents, great-grandparents, great-great grandparents, etc.  The DNA that they didn’t pass down to us cannot be analyzed, of course.

So, when I get an e-mail from someone who is really angry about the fact that their ethnicity result showed no Italian DNA when they know for sure that their great-great grandmother was actually born in Italy, I know just what happened.

Myth #5  An ancestor born somewhere is “100%” from that region

If I have six great-great grandparents who were born in Germany, does that mean I should show 37.5% Germanic Europe DNA on my DNA results?  I certainly could show this amount of DNA from that region, but to be truthful, it’s unlikely that I would (spoiler alert:  I don’t).  Why?

Fact:  Your ancestor might have had DNA from a few different regions, and thus was not “100%” any particular region

You already know that I didn’t inherit DNA equally from all of my ancestors because each generation 50% of DNA isn’t passed down, but there is also one more important consideration to consider:  My German ancestors might not have been 100% German.  They might have had Eastern European DNA, or DNA from France, or Denmark, or any other nearby, or even not nearby region.

Our ancestors were more mobile than we tend to think that they were, despite the how difficult it was to travel long distances.  This means that they were also more “admixed” than we might imagine, sharing DNA with regions other than the ones where they lived.


I hope that this post has helped you understand some of the myths behind ethnicity estimates, and what the real facts are.  If you have any questions about something that I mentioned in this post, or if you would like to talk about your own ethnicity estimate, I would love to hear from you in the discussion below.

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