23andMe's Ancestry DNA Test Just Got a Lot More Precise

By Kristen V Brown on at

If you’ve ever taken an ancestry DNA test, you probably already know that the results aren’t exactly precise. Sometimes you wind up with completely different results than you expected. And different brands of DNA tests can beget entirely different results.

On Wednesday, though, 23andMe announced an update to its service that should give customers more specific insight into where they are from. Rather than telling a customer that they are, say, “Scandinavian,” that customer might find that they are specifically part Norwegian. All told, the company has added 120 new geographic regions to the results of its test. That’s a big upgrade from the 31 population labels 23andMe employed before.

The update is thanks to a major expansion in the number of people in 23andMe’s reference population, the data set of DNA which 23andMe’s algorithm measures your DNA against to determine where in the world you match. The growing number of people that have taken the company’s test and shared information about their heritage helps to fine-tune that algorithm, too.

When I took 23andMe’s test last year, as part of a story I did on the accuracy of ancestry tests, the test was surprising because it told me I was only 3 percent Scandinavian and 5.5 percent Middle Eastern, even though I expected numbers much higher in those areas based on my family history. The majority of my DNA fell into wide categories like “Broadly Northwestern European.” And low amount of Middle Eastern DNA was likely due to a smaller representation of people from that region in 23andMe’s data.

The author’s 23andMe test results from last autumn.

With the update, the picture 23andMe painted of my ancestry was closer to the one painted by family genealogy. It was also more specific. It was able to tell me not just that I was Scandinavian and Middle Eastern, but that I’m Norwegian and Syrian.

The author’s 23andMe data from this week.

“We can do this by looking for exact DNA matches between a customer and over 130,000 individuals of known ancestry from 120 regions across the globe,” the company said in a blog post. “If a person exactly matches with five or more individuals from one of those specific regions, that region is assigned as a ‘recent ancestor location.’ We also report the ‘strength’ of the match, which is determined by how much DNA a customer shares with people from that region, adjusted by how many people are in the reference population.”

The company noted that it has also “relabelled some of the populations for accuracy and better understanding,” such as the Yakut, which now appear as Siberian. The update will gradually roll out over to customers in the coming months.

The update to 23andMe’s test is a good example of how rapidly genetic technology is improving, and how with technological advances and larger data sets, consumer DNA testing stands to get a lot more precise. The results of my own test were much more specific and seemed to be more accurate, based on my family’s known history, than my results of just a few months ago.

But, in my case, the percentages of Middle Eastern and Scandinavian still were significantly lower than I would expect, a reminder that ancestry DNA tests should still be taken with a fairly large bucket of salt. Heritage DNA tests are still far more accurate for some groups of people than others. And even at their most accurate, they will still only be able to tell you how closely your DNA resembles other people in the world today, not where your ancestors are from. If you go back far enough, we’re all related. The vast majority of our DNA is the same.

It bears repeating: Your DNA is part you, but it will never define you.