23andMe is one of the most popular consumer DNA tests in the world. People wonder how accurate its ancestry and ethnicity reports are. We have answers.
Recently, we published an article describing various ways a consumer DNA test for family history can be wrong—and about how much of the time, they’re not actually wrong. You just have to learn to understand what they’re saying. You might want to read that article before you continue reading specifically about how accurate 23andMe is. Go ahead—we’ll wait. But definitely come back. Because we have more to say specifically about 23andMe.
23andMe: How accurate are the results?
When people ask how accurate 23andMe tests are, they could be thinking of many kinds of results you get, including:
- Ethnicity reports
- DNA Relatives
- Family Tree
- Health & Traits reports
We can’t cover all of these in one article. And as a nonmedical resource, we don’t analyze the Health & Traits part at all. But here are the highlights of the most accurate, meaningful family history information you should consider.
23andMe Ethnicity: Countries and Groups
When you take a 23andMe DNA test for family history, your results include information about your ancestral locations and ethnicities. While you might be curious about your Neanderthal ancestry, maternal and paternal haplogroup (deep-ancestry) reports, the most detailed information you get on ancestral locations is in your Ancestry Composition Report. But generally, these estimates are looking at the past several hundred years or more.
However, many people care most about recent ancestry: where their relatives may have lived within the past 200 years or so. For that, you’ll want to look closely at the Countries and Genetic Groups that are embedded within your Ancestry Composition Report. The countries and groups are not based on how well you resemble a reference population, but how you actually match with specific members of that reference population. The more people you match, and the more DNA you share with those specific people, the higher confidence 23andMe has in your connection to that place. They rate that confidence according to three levels: possible, likely, or highly likely.
In the summary view shown below left, you’re seeing my Country match for French & German (they’re combined because they share so much DNA, historically). If I click on French & German, I’ll see a new window showing Germany with a likelihood indicator (here, “highly likely match”), and a mapped list of the 4 specific regions with which my DNA is recently associated:
Things to know:
- These results come from looking for identical pieces of DNA you share with more than 400,000 people of known ancestry from around the world.
- The likelihood indicators tell you how confidently 23andMe is assigning you to these locations, based on multiple criteria. The “highly likely” indicator I got for Germany means they are at least 80% confident of this assignment. Other indicators are: “likely (50-79%); “possible” (30-49%), and “not detected” (less than 30%).
- These are often very specific places! It’s a great clue if you’re tracing your family tree or just trying to learn where your relatives come from. If you’ve never heard about your relatives being from this part of the world, remember that a lot of people don’t know the correct origins of ALL their biological great grandparents and beyond. An unfamiliar location may represent an ancestor you just haven’t learned enough about yet.
23andMe’s DNA Relatives
At 23andMe, you opt-in to seeing your DNA Relatives (Settings > Privacy & Sharing > DNA Relatives (click Manage Your Preferences) > Yes). When you turn this feature on, you’ll be able to see a list of people who have also tested there who share a significant enough amount of DNA with you that you are likely related.
The “predicted relationship” between you and a match is an estimate based on how much DNA you share. As shown below, clicking on one of your DNA Relatives will bring up an illustration of how you may be related. But as explained in the yellow-highlighted area, the “2nd Cousin” prediction shown here represents one of many possible genealogical relationships that include half- and removed relationships that would result in about the same amount of shared DNA as an actual second cousin.
So, how accurate are these predicted relationships with your DNA Relatives? They are estimates only. You have to do additional research to see where exactly you fall on each other’s trees.
Family Tree
The last thing we’ll cover is 23andMe’s Family Tree tool. Mine looks like this:
If you know anything about genealogy, STOP in your tracks. This family tree is different than you’re used to. 23andMe’s Family Tree tool is an automatically-generated family tree based on your 23andMe DNA connections. Pause and let that sink in. This is not a traditional family tree based on historical research or family knowledge. It takes your DNA Relatives (3rd cousins or closer who have opted into DNA Relatives) and places them into the most likely tree configuration based on your shared DNA and ages. (And you just learned that the shared DNA only generates a predicted relationship, which can be wrong.)
23andMe knows it’s guessing, so it has added the capacity for you to tinker with the Family Tree. To move DNA Relatives around to the proper spots (once you figure those out). To add genealogical data if you like.
So, how accurate is 23andMe?
As you’ve seen, it depends on what part of your results you’re asking about. In summary:
Recent Ancestor Locations (or specific regions) on your Ancestry Composition Report are typically the most accurate and meaningful connections to ancestral places within the past 200 years or so.
Your list of DNA Relatives does accurately state how much DNA you share with each match. This leads to a predicted genetic relationship, which may be correct but mostly represents the ballpark of genetic distance you have from that person (“we share about the same amount of DNA as 2nd cousins”).
Your Family Tree is a convenient, automatic reconstruction of a possible family tree, based on your 23andMe connections. It may be right, and it may require some tweaking. Maybe a lot of tweaking.
