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Understanding DNA Ethnicity Estimates
As an amateur genealogist, 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 usual response is the desire to simply receive an ancestry DNA ethnicity estimate. There are several key factors that need to 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 flippantly, and instead it should be treated deliberately and soberly. Why? Some have made life changing family discoveries from DNA matching. Another key factor is the recognition and understanding of how an ancestry DNA ethnicity estimate is actually determined. The photo shown above is a stock photograph, which was sourced here.
There are actually three different types of consumer ancestry DNA tests available, which are an Autosomal DNA (atDNA) test, a Y-Chromosome DNA (Y-DNA) test, and a Mitochondrial DNA (mtDNA) test. The most commonly used and most affordable type of DNA test is an Autosomal DNA (atDNA) test, which provides an ethnicity estimate and DNA matching. The other two test types are only offered by selected companies, and are intended for advanced genealogical research. The Y-Chromosome DNA (Y-DNA) test can only be taken by a male family member, and examines the Y-Chromosome which is transmitted from father to son, generation by generation, and enables the tracing of a common paternal ancestor. The Mitochondrial DNA (mtDNA) test can be taken by anyone, and examines the Mitochondrial DNA which is transmitted from mother to child, generation by generation, and enables the tracing of a common maternal ancestor.
One of the most common reasons for taking an ancestry DNA test is to simply receive an ethnicity estimate, and this could be loosely described as a novelty user. This is because the novelty user frequently looks at it as a "one time curiosity thing," and has no intention of actually researching their family tree. 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 usually don’t realize the following four key things about ancestry DNA ethnicity estimates.
DNA ethnicity estimates will vary between testing providers
DNA ethnicity estimates will vary between siblings
DNA ethnicity estimates will update over time
DNA ethnicity estimates are only estimates
Misconceptions about DNA originate from television, movies, and the mainstream media which inaccurately portray it as being exact in all regards, as well as the marketing hype from DNA test providers who have to simplify the messaging for advertising purposes. There is frequent disappointment after someone takes an ancestry DNA test, as well as many resulting questions, so it is my hope that some may find this article informative before they decide to take a test. The information below is first hand, 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 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. Each ancestry DNA test provider devises algorithms to compare the DNA of the person being tested with the DNA of reference groups or panels of living individuals, and these methodologies are still evolving.
The following table provides a first hand example of how ancestry DNA ethnicity estimates will vary by test provider. The table shows my current ethnicity estimates side by side from AncestryDNA, 23andMe, and FamilyTreeDNA. Note the variations in the categorized regions and the particular percentages. Another factor to keep in mind that each provider will use a different breakdown of geographic regions and countries.
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 for the variation is genetic inheritance and the random nature in which DNA is received from each parent. From a simplistic perspective, each child 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, and as a result, the ethnicity estimates will vary even if the same test provider is used.
The following table provides a first hand example of how ancestry DNA ethnicity estimates will vary between siblings. The table shows the ethnicity estimates from AncestryDNA side by side for my late father and his three siblings Note the variations in the categorized regions and the particular percentages.
It should also be recognized that for the purpose of an ancestry DNA ethnicity estimate, the DNA of siblings is not compared with each other, and is only individually compared by algorithms with the DNA from reference groups. The randomness of the genetic inheritance is also important to understand in regards to DNA matching. If someone begins to research their family tree via traditional paper trail research, DNA matching can carefully be applied in light of that research. There is significant value in having multiple family members tested for the purpose of DNA matching. The reason is the randomness of genetic inheritance, 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 Update Periodically
Many do not realize that ancestry DNA ethnicity estimates will be updated over time. 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. Each ancestry DNA test provider devises algorithms to compare the DNA of the person being tested with the DNA of reference groups or panels of living individuals, and these methodologies are still evolving. As more people get tested and as those methodologies are improved, the expectation should be that your ethnicity estimate will be updated periodically. For example, my ethnicity estimates from AncestryDNA, 23andMe, and FamilyTreeDNA have all been updated multiple times.
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 ancestry DNA test provider (AncestryDNA, 23andMe, and FamilyTreeDNA), and vertically shows how each was updated at different points in time.
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 the ethnicity estimates from AncestryDNA side by side of my late father and his three siblings, 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 they are simplifying the subject matter for a 30 second television commercial. Unfortunately, this is somewhat misleading, as the ethnicity percentage breakdown from a DNA test can’t be deciphered with a high degree of certainty and there are margins of error. Similarly, DNA is inaccurately portrayed by television, movies, and the mainstream media. For example, DNA matching can’t determine an exact relationship other than that of parent and child.
By now you may be wondering exactly how is an ancestry DNA ethnicity estimate actually determined and calculated. The methodology used to determine an ethnicity estimate varies between the ancestry DNA testing providers, and largely consists of algorithms where the DNA of the person being tested is compared with the DNA from reference groups determined by each provider. The reference groups, which are also known as reference panels, consist of the DNA of living individuals. Each provider screens candidates for their reference panels in regards to their ancestry and what is known about their family trees, and cross references them together via algorithms to calculate the estimates. It would be a misconception to think that your DNA is compared with that of someone who died centuries ago, such as that obtained from old bones. Most of the testing providers state that their reference groups enable an estimate that goes back roughly 500 years. In the end, they are only wide ranging estimates.
If your only intended purpose for taking an ancestry DNA test is to get an ethnicity estimate, you should now recognize that the estimate will vary based on the test provider, the estimate will vary between siblings, the estimate will be updated over time, and that 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 with AncestryDNA. Rarely do I even look at the ethnicity estimates, as the true and long term value is with the application the DNA matches to my 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 a trait and health 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 on Ancestry to directly integrate a family tree with DNA matching. Additionally, roughly twice as many people are said to have been tested on Ancestry, so if DNA matching will be of interest, there should be a significantly greater number of matches on Ancestry.
The following links provide additional reference and reading on some of the differences between the DNA test providers.
The DNA Geek: DNA Tests (August 2022)
CNET: Best DNA Test for 2022: AncestryDNA vs. 23andMe and More (August 11, 2022)
CNET: Ancestry vs. 23 and Me: Which DNA Testing Kit is Best for Tracing Your Family's Roots? (September 3, 2021)
Time: You Can Learn a Lot About Yourself From a DNA Test. Here’s What Your Genes Cannot Tell You (March 2, 2020)
PCWorld: 23andMe vs. AncestryDNA: Which Ancestry DNA Kit is Better? (December 11, 2019)
Family Tree Magazine: Fact or Science Fiction? Putting DNA Rumors to the Test (October 2019)
Vox: The Limits of Ancestry DNA Tests, Explained (May 23, 2019)
Genealogy Explained: 23andMe vs. AncestryDNA (March 8, 2018)
The following links provide additional reference and reading on why DNA ethnicity estimates will vary by sibling.
Ancestry: Unexpected Ethnicity Results
Genealogy Explained: Do Siblings Have the Same DNA? (July 16, 2018)
The following links provides additional reference and reading on why DNA ethnicity estimates will be updated periodically.
Insider: People's DNA Ancestry Results Keep Changing as the Sites Gather More Data: 'What's My Real Identity?' (June 25, 2019)
USA Today: Ancestry.com's Ethnicity Updates Likely Won't Be the Last (September 25, 2018)
CBC News: Did your Ancestry.com DNA results change dramatically? Here's why (September 17, 2018)
The following links provides additional reference and reading on how a DNA ethnicity estimate is calculated and determined.
The DNA Geek: Ethnicity Schmethnicity (September 20, 2021)
Ancestry: What is an Ethnicity Estimate?
Ancestry: AncestryDNA Ethnicity Estimates Now Provide Even Greater Precision
Ancestry: AncestryDNA Ethnicity FAQ
Ancestry: AncestryDNA White Papers
23andMe: Ancestry Composition
23andMe: Ancestry Composition: 23andMe's State of the Art Geographic Ancestry Analysis
Should you any questions, comments, or corrections, please feel free to e-mail me or make a comment below. Again, I make no claim of being a genetic subject matter expert. I’m simply an amateur genealogist and attempted to summarize some information which I believe to be accurate and helpful.
Footnote: Further Details on Your DNA Ethnicity Estimate
Ethnicity estimates provided by all ancestry DNA test providers will have further details and learning information available your fingertips. Some users only look at their ethnicity estimates on mobile phone apps, which can limit the type and breadth of details that might be available, so they are best viewed on the website of the test provider. Some users do not recognize that each region and percentage can be clicked on to receive further details, and this is important as looking only at the region names and percentages can be misleading.
For example, if you tested with AncestryDNA and "Scotland 15%" was listed in your ethnicity estimate, you can click on it and the following screen would be displayed. AncestryDNA provides at least three additional data points, which are highlighted with the red arrows. First, it will show a map of the respective region and how far it can actually span. In this particular example, the AncestryDNA estimate for "Scotland" can span into parts of England, Northern Ireland, and France. Second, AncestryDNA provides a margin of error in their estimates, and that can be clicked on for further information. Third, there will be "About this Region" and other items which can be clicked on, such as "Learn more about this map and ethnicity." Again, all ancestry DNA test providers provide further details on each region and percentage in their ethnicity estimates, which will help explain how it is only just that, an estimate.
© Copyright - Timothy J. Barron - This page was updated March 12, 2023