How Accurate is 23andMe?

Written by Lewis Cuthbertson, PhD | Last updated:

The major benefit of using a service like 23andMe is they analyze complicated data and give you results in an easy to understand format about your health and ancestry, but how accurate is 23andMe, and are they worth it? Read on to find out more.

How does 23andMe process your data?

DNA testing is a complex process, so the first thing you need to understand in order to discuss the accuracy of any DNA testing service that provides health and ancestry information is how this data is generated.

23andMe tests 650,000 genetic variants or SNPs, but all in, this accounts for just 0.023% of your entire DNA. Even though our understanding of DNA has progressed well over recent years, there is still a lot to learn.

This is why 23andMe only tests 0.023% of your DNA – there are still a lot of insights into your health and ancestry to be gained from this small portion. Despite the fact that this is just a tiny percentage of your DNA, the data is still massive. So what do we mean when we question the accuracy of 23andMe, what can actually vary?

Processing your DNA sample

23andMe uses a process known as genotyping to test your DNA. When you provide your saliva sample to 23andMe, this is sent to a lab where they extract your DNA and use a genotyping machine to identify which of the 650,000 SNPs you carry.

This type of analysis is around 99% accurate, so the variation in this data is fairly standard and isn’t concerning, you can be fairly certain that if 23andMe reports you have a particular SNP, then this is true. You can read this post to learn how DNA tests work.

How accurate is 23andMe ancestry reporting?

When it comes to ancestry in particular, how accurately you can predict someone’s heritage is largely influenced by how good the reference dataset is. Oversimplifying the process, your heritage is identified by comparing your DNA data to that of others and seeing which yours is most closely matched to. So when it comes to ancestry, how accurately your heritage is reported is largely dependent on how large and well maintained the comparable dataset is.

Imagine for example you are from Spain and know you have a long family history there, but the company you have chosen to analyze your DNA uses only British DNA data to identify your heritage, then it’s likely that you will be identified as being British.

Thankfully, 23andMe has the second biggest DNA database in the world only behind Ancestry.com, so you can be highly confident that your reported heritage is the most accurate it can be with the current tools available.

How accurate is 23andMe health reporting?

Once your DNA has been processed, 23andMe then uses statistics to analyze your genetic data and identify which traits and health conditions you may be predisposed to based upon data from large scale scientific studies. These studies, often referred to as GWAS, use complex statistical methods to identify relationships between genetic variants and health conditions.

The accuracy of the findings within these studies can depend on certain factors such as how many people participated or how many ethnicities were tested. The best way to identify how strong an association is based on a study is to go directly to the source, and 23andMe directly links the studies they reference in their health reports.

It’s also important to remember that most of the associations identified in these types of study are relative rather than absolute, which is what causes a lot of skepticism from customers about 23andMe accuracy, because of course if you’re told you should like coffee based on your genes but have never drunk a cup in your life this can’t be accurate, can it?

But just because you are more likely to like coffee based on an SNP you carry, that doesn’t mean that you definitely will. Your likelihood of expressing any trait or health condition is highly complex because it is influenced by your environment too, i.e. your diet and lifestyle. So is 23andMe accurate if they report that you are more likely to like coffee based on your DNA even if you don’t drink it?

The answer is definitely yes, relatively speaking.

Let’s explain why…

The large scale studies from which these links are discovered take a bunch of people with variant X and a bunch of people with variant Y, and test to see whether carrying variant X is associated with a certain trait (like coffee drinking). If significantly more people with variant X drink coffee, then this variant is said to be linked to the trait.

But that doesn’t mean that all of the people with variant X liked coffee, nor does it mean that those with variant Y did not, it just means that more people with variant X in this study liked coffee relative to those who had variant Y.

This all being said, 23andMe does have one major drawback when it comes to health reporting in that they only investigate 1 or 2 variants per health condition. Whilst for some conditions like cystic fibrosis, only one variant may be the culprit, but most aspects of health like weight management or mood are complex and influenced by a larger number of genes.

Other companies such as SelfDecode take a more comprehensive approach by using AI and machine learning to predict up to 83 million genetic variants with 99.7% accuracy from your typical DNA file, like from 23andMe. This means that SelfDecode can give you a more complete picture of your health than other DNA companies.

Human error

Of course, no matter how accurate the technologies underpinning your genetic analyses are, there is always a small chance that your data could be subject to human error at any stage of processing. The good news is that 23andMe has outlined their quality review process on their website, so they’re doing everything they can to avoid this.

How accurate is 23andMe

Alternatives to 23andMe

If you’re interested in receiving recommendations based on your genes, there are some alternatives you should consider. 23andMe provides health insights based on just 1 or 2 variants, which could result in incomplete and misleading results. Other providers of DNA wellness reports such as SelfDecode can investigate thousands or even millions of genetic variants per report in order to provide you with the most accurate health data.

SelfDecode uses predictive algorithms to analyze up to 83 million genetic variants (~1 million per wellness report), giving you the most accurate health data based on your genetics. Not only this, but their wellness reports include personalized recommendations to counteract specific problematic genetic variants, rather than generic recommendations, giving you the best in precision medicine.

If you have a 23andMe raw DNA file, you can upload it to SelfDecode to receive your health insights. However, if you still haven’t had your DNA tested, SelfDecode also offers DNA testing.

Takeaway: Is 23andMe accurate?

So how accurate is 23 and Me? When it comes to investigating your heritage, 23andMe is as competitive a company as you could hope for, boasting the second largest reference database of genetic data and providing you with a highly accurate understanding of your genetic heritage.

When it comes to health reporting however 23andMe does have one drawback as currently they only investigate a limited number of genetic variants for certain health conditions which are much more complex, meaning that whilst the data they provide for these few variants is an accurate representation, it may be misleading. If you would like a more comprehensive and accurate insight into your health based on your genetics, consider trying a service like SelfDecode.


About the Author

Lewis Cuthbertson

Lewis completed his PhD in Molecular Microbiology at Northumbria University (UK). Lewis spent several years researching the biodiversity of bacterial communities in the Arctic and Antarctic, whilst also performing research for a DNA sequencing service, where he was involved in several health based microbiome studies. This gave him an insight into how the highly diverse and invisible to the naked eye portion of human health, can potentially impact an individual’s quality of life, driving his desire to help others understand their own complex health needs through the most current scientific research.


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