Understanding DNA Ethnicity Estimates

As an amateur genealogy enthusiast, I am frequently asked which ancestry DNA testing company is the "best" to use. One of the first things that I inquire about are the person’s reasons and purpose for taking a ancestry DNA test, and the common response is the simple desire to receive an DNA ethnicity estimate. This page provides some helpful background information on DNA ethnicity estimates, and helps address some common misconceptions. I make no claim of being a genetic subject matter expert, as I’m simply an amateur genealogy enthusiast and have summarized some information which I believe to be helpful. The photo shown above is a stock photograph, which was sourced here.

Introduction to DNA Ethnicity Estimates

Before taking a DNA test, there are a couple of key factors that should be understood so that expectations are properly set. The first key factor is the recognition of basic common sense. Some treat an ancestry DNA test somewhat flippantly, and instead it should be treated deliberately and soberly. Why? Some have made life changing family discoveries from DNA matching. The second key factor is recognizing how ancestry DNA ethnicity estimates are actually determined, which this article will help address. Unfortunately, some only pursue this knowledge after taking a test, and this can result in varying levels of disappointment.

The most common reason for taking an ancestry DNA test is the simple desire to receive an ethnicity estimate. This could loosely be described as a novelty user, as the test is being considered as a one time curiosity thing, and there is usually no intent of doing any family tree research or applying DNA matches to that research. Any of the testing providers of an Autosomal DNA (atDNA) test will provide an ethnicity estimate. Before even considering which DNA test provider to use, my experience and observation is that most novelty users don’t realize the following five key facts about ancestry DNA ethnicity estimates.

DNA ethnicity estimates will vary between testing providers
DNA ethnicity estimates will vary between siblings
DNA ethnicity estimates will not equate to parents
DNA ethnicity estimates will be updated periodically
DNA ethnicity estimates are only estimates

Each of these five facts are addressed individually further below. All of the data shown is from my own testing, as I’ve taken ancestry DNA tests from multiple test providers, and had multiple family members tested.

DNA Ethnicity Estimates Will Vary Between Testing Providers

Many do not realize that ancestry DNA ethnicity estimates will vary between testing providers. The reason is that each ancestry DNA testing provider has to create their own methodologies to calculate an ethnicity estimate, which is only just that, an estimate. Each ancestry DNA test provider devises their own unique breakdown and labeling of geographic regions. Then they construct references panels of living individuals to represent each geographic region. Then they create algorithms to to compare the DNA of the person being tested with the DNA of those living individuals from the reference panels. It is a misconception that an ethnicity estimate is determined by comparing your DNA to that of someone who died centuries ago, such as that obtained from bones.

The following table provides a first hand example of how ancestry DNA ethnicity estimates will vary by test provider. The table shows my ethnicity estimates side by side from AncestryDNA, 23andMe, MyHeritage, and FamilyTreeDNA. Note the variations in the categorized regions and the particular percentages. Some of the testing providers do provide a further breakdown of specific areas, but this illustration does not include those for the purpose of simplicity .

One way of determining your ethnicity with a degree of certainty is to perform traditional paper trail research of your family tree, which can be combined with the the careful application of DNA matches. My extensive paper trail research shows that I’m nearly one-half British, along with Polish (1/4 or 25%), German (1/8th or 12.5%), Swedish (1/8th or 12.5%), and splashes of both Irish and French. When the above ethnicity estimates are compared in the light of my paper trail research, this provides a comprehensive first hand demonstration of the degree of accuracy in which an ethnicity estimate should be evaluated.

DNA Ethnicity Estimates Will Vary Between Siblings

Many do not realize that ancestry DNA ethnicity estimates will vary between siblings. The reason is the randomness of genetic inheritance and how DNA is inherited from each parent. From a simplistic perspective, everyone receives a random 50% of their father’s DNA and a random 50% of their mother’s DNA. Due to the random nature of genetic inheritance, each sibling could inherit different segments or markers of DNA from their parents that their other siblings do not have. As a result, ethnicity estimates will vary by sibling even if the same test provider is used. Ancestry provides further explanations in the articles Understanding Inheritance and Unexpected Ancestral Regions from their support site

The following table provides a first hand example of how ancestry DNA ethnicity estimates will vary between siblings. The table shows the ethnicity estimates side by side from AncestryDNA for my late father and his three siblings Note the variations in the categorized regions and the particular percentages, such as how only one has Iceland, and similarly only one has Cornwall.

Another key aspect to recognize with DNA ethnicity estimates is that the DNA of siblings is not compared with each other in any way, and is only compared with the DNA of living individuals from the reference panels. Obviously, the DNA of siblings is compared with each other in regard to DNA matching. The randomness of the genetic inheritance is an important factor to understand with DNA matching. There is significant value in having multiple family members tested for the purpose of DNA matching, as distant relatives may show as a DNA match for one family member but may not show as a DNA match with another.

DNA Ethnicity Estimates Will Not Equate to Parents

Many do not realize that ancestry DNA ethnicity estimates will not equate or be a simple average of their parents if they are also tested. As described above, the reason for this is the randomness of genetic inheritance and how DNA is inherited from each parent.

The following table provides a first hand example of how ancestry DNA ethnicity estimates will not equate or be a simple average of parents if they are tested. The table shows the ethnicity estimates side by side from AncestryDNA for my late father, my mother, and myself Note how my percentages do not equate to be a simple average of my mother and father, nor are they in the same order if they were averaged. Also note how I have a couple of low percentage regions that neither of them have. Ancestry provides an explanation for this in the article Regions by Parent from their support site.

As summarized above, the DNA of siblings is not compared with each other in any way for an ethnicity estimate, and the same is true with any family member, such as parents. For an ethnicity estimate, the DNA of the person being testing is only compared with the DNA of living individuals from the reference panels.

DNA Ethnicity Estimates Will Be Updated Periodically

Many do not realize that ancestry DNA ethnicity estimates will be updated periodically. The reason for this is that each ancestry DNA testing provider has to create their own methodologies to calculate an ethnicity estimate, which is only just that, an estimate. As summarized previously, each testing provider devises their own geographic regional breakdown, their own reference panels with the DNA of living individuals to represent each region, and then their own algorithms where the DNA of the person being tested is compared with the reference panels. All of these methodologies are still evolving and each testing provider may update theirs at any time, so the expectation should be that your ethnicity estimate will be updated periodically and the results will change.

The following table provides a first hand example of how ancestry DNA ethnicity estimates will be updated periodically. This table actually serves a dual purpose, as it horizontally shows how my own ethnicity estimates vary by DNA test provider, and shows how each was updated at different points in time.

The following table provides another first hand example of how ancestry DNA ethnicity estimates will be updated periodically. This table actually serves a dual purpose, as it horizontally shows the ethnicity estimates side by side of my late father and his three siblings from AncestryDNA, and vertically shows how each was updated at different points in time.

DNA Ethnicity Estimates Are Only Estimates

Most don’t realize that an ancestry DNA ethnicity estimate is only just that, an estimate, and an inexact and wide ranging estimate. The marketing hype and advertising from the DNA testing providers may highlight someone saying that they are 43% of something, but the subject matter is being simplified for a 30 second television commercial. Unfortunately, this is somewhat misleading, as the regions and percentage breakdown from a DNA ethnicity estimate are inexact and there are margins of error. Ancestry is one test provider that actually does calculate and provide margins of error.

Summary

If your only intended purpose for taking an ancestry DNA test is to get an ethnicity estimate, you should now recognize how a DNA ethnicity estimate is actually determined and calculated. You should now recognize that it will vary by test provider, it will vary by sibling, it will not equate with your parents, and it will be updated periodically over time. Ultimately, you should now also recognize how the estimate is only just that, an estimate. This largely serves as the overall intent of this article. Beyond the novelty aspect of having an ancestry DNA test done, hopefully you will eventually gain some interest in researching your family tree. Besides getting myself tested, I’ve had seven other family members tested. Rarely do I even look at the ethnicity estimates, as the true and long term value is with the application the DNA matches to family tree research.

As to answering the proverbial question of which test is "best," there are multiple dependencies. For just an ethnicity estimate, both Ancestry and 23andMe regularly flip flop as to who has the most reference groups and regions from which they devise their estimates. Some testing providers also have additional features to consider, such as health or trait analysis. If you think that you might have a future interest in researching your family tree, that is where I would strongly recommend AncestryDNA, as there are features to directly integrate a family tree with DNA matching. Additionally, roughly twice as many people have been tested on Ancestry, so if DNA matching will be of any interest, there should be a significantly greater number of matches to explore on Ancestry.

The following links provide additional reference and reading on DNA ethnicity estimates.

Ancestry: Understanding Inheritance - this article from the Ancestry support site explains the randomness of genetic inheritance
Ancestry: Unexpected Ancestral Regions - this article from the Ancestry support site explains several aspects of ethnicity estimates
Ancestry: Why Is My Percentage for an Ancestral Region Higher (or Lower) Than My Family Tree Suggests It Should Be?
Ancestry: Regions by Parent - this article from the Ancestry support site explains how DNA from nearby regions can look similar
The DNA Geek: DNA Tests - this article from Dr. Leah Larkin summarizes the number of people that have been tested by test provider
The DNA Geek: Ethnicity Schmethnicity - this article from Dr. Leah Larkin explains why ethnicity estimates vary by test provider

Should you any questions, comments, or corrections, please feel free to contact me. Again, I make no claim of being a genetic subject matter expert, as I’m simply an amateur genealogy enthusiast and attempted to summarize some information which I believe to be accurate and helpful.