Remember when you got your AncestryDNA® test results? You likely recall the anticipation, the excitement of what you might discover—and the fun of sharing your ethnicity estimate results with family.
But what people often don’t realize is how much information is contained in their ethnicity estimate. An ethnicity estimate actually has two major pieces of information—ethnicity regions and communities. We are going to talk about ethnicity regions here.
Ethnicity regions are the most well-known part of the ethnicity estimate and come with percentages, like 25% Sweden or 10% Ivory Coast & Ghana.
They are really broad; they often encompass one or more modern day countries. And they often reach back more than 20 generations.
Communities are the second piece of your AncestryDNA ethnicity estimate. Unlike ethnicity regions, communities are not assigned percentages. What they are is more precise areas of the world, to give you a more granular understanding of where your ancestors came from (sometimes down to the region of a country or even a county). And they’re also from the more recent past, about 5-20 generations ago.
Here we are going to focus on the ethnicity regions.
How does AncestryDNA assign ethnicity regions in your ethnicity estimate?
Assigning ethnicity regions based on your DNA sample is a complex process based on probability, statistics, shared DNA, and ongoing research and science.
First our scientists create a reference panel, which is made up of reference groups. Each reference group has the DNA of people whose family lived in a certain part of the world for many generations.
And each reference group represents an ethnicity region.
As of 2020, there were 70 reference groups in the AncestryDNA reference panel.
When a customer takes an AncestryDNA test, our scientists compare their DNA, piece by piece, to see which reference group each piece of that customer’s DNA most closely resembles. The ethnicities assigned to each piece of DNA are then totaled up and the percentages are calculated. If 15% of the DNA pieces analyzed look most like the France reference group, then the customer gets 15% France in their ethnicity estimate.
AncestryDNA continues to add samples and update its reference groups to improve precision and include additional ethnicity regions in AncestryDNA test results. Additionally, AncestryDNA can update the way it analyzes your DNA.
The updating of reference groups and the way the DNA is analyzed means that over time, your results may be updated too.
Here’s a simplified example of how the AncestryDNA algorithm assigns ethnicity regions. The algorithm looks at about 700,000 markers in your DNA sample. Those markers are called SNPs (pronounced snips). Each SNP refers to a certain position in human DNA. And each SNP is made up of a pair of letters representing some combination of A, T, C, or G. Let’s say that at SNP rs122 there are two possibilities: A and T. Because you get one letter (or allele) from each parent, you can have an AA, AT, or TT.
Each possible outcome at each SNP has a probability for how likely it is to show up in each region represented by the reference panel. We’ll pretend that rs122 occurs in three populations—Indigenous Americas—Mexico, Sweden, and Scotland—at the following frequencies:
A = appears 5% of the time in Indigenous Americas—Mexico populations, 75% in Swedish populations, and 80% in Scottish populations.
T = appears 95% of the time in Indigenous Americas—Mexico populations, 25% in Swedish populations, and 20% in Scottish populations.
So, if you have AA at rs122, it seems that that specific part of your DNA is more likely to be Swedish than Indigenous Americas—Mexico. If your DNA reads TT, the opposite seems more likely. One SNP doesn’t tell us much about your ethnicity, but when we apply the same process to thousands of SNPs, and then do the math, the grand total becomes the basis for your ethnicity estimate.
Why do ethnicity estimate percentages have a range and how is it determined?
In addition to the most likely estimate, our algorithm also generates 1,000 likely estimates using the probabilities learned from comparing your genetic data to our reference panel.
We use these 1,000 likely estimates—which may be different from the most likely estimate—to figure out the range. The way we calculate the range will depend on the region and the value of the most likely estimate.
Here’s an example of an AncestryDNA ethnicity estimate for someone with strong ties to Europe and the Americas.
In the example above, between 50% and 55% of this customer’s DNA appears to match the Ancestry Indigenous Americas—Mexico reference panel, with an average percentage of 53%.
That 53% is the most likely number within a range of percentages that are also likely. Less likely, but not necessarily by much. To find out your range of likely percentages, click on the ethnicity in your results that you are interested in.
These ranges are important to look at, especially for results with lower percentages. In these cases, the range can sometimes include zero. This means that for these results, it is possible that your ancestors didn’t live in that region or you didn’t inherit any DNA from ancestors who did.
But My Family Never Lived in [Your Mystery Region Here]
Here is an example of someone with 7% Norway in their results.
But what if they've never heard of anybody in the family being from Norway? This is where the maps and the polygons on them can help. By clicking on Norway, the first thing that pops up is a note that this ethnicity is found primarily in Norway, Iceland, and Faroe Islands. OK, so already there are new possible places the ancestor who passed this down might be from.
And a close look at the map shows that other places are possible too—for example, Denmark and parts of Sweden.
This all makes sense when you consider that Norwegians, Swedes, and Danes all share a common Norse heritage. For centuries, hunter-gatherers pushed north across the Baltic Sea, probing coastal fjords and inland stretches for farmable land. By the 9th and 10th centuries Norwegian Vikings colonized the Faroe Islands, Iceland, and Greenland (along with northern Scotland, the Orkneys, the Hebrides, and the Isle of Man).
So, your ethnicity estimate can provide insight not only on where your ancestors might have lived but also allow you to trace the path of your ancestors.
When Did All This Happen?
Your genetic ethnicity estimate tells you about your possible historical origins, not necessarily about where you live today. AncestryDNA genetic ethnicity estimates go back hundreds to more than a thousand years, when populations and their boundaries were often very different. This might lead to a different genetic ethnicity estimate than you might expect.
But while someone’s language, name, or culture may change when they move to a new location, their DNA doesn’t. This can lead to surprises in your genetic ethnicity. For instance, if the ancestors of your Italian ancestors migrated from Eastern Europe hundreds of years ago, you might show up as having Eastern European ethnicity instead of Italian.
The opposite can also happen. DNA is passed down randomly and the amount of DNA you might inherit from any particular ancestor decreases with each generation. That means you can have an ethnicity you know of in your family history that doesn’t show up in your ethnicity estimate.
If you haven’t looked at your ethnicity results in a while, go back and give them another look. You’re much more than a pie chart and a handful of percentages. And so is your AncestryDNA ethnicity estimate.