Think Before You Spit: A Guide to Understanding At-Home DNA Testing Kits

Direct-to-consumer (DTC) genetic testing, or testing that can be ordered from your home without a medical provider, has blown up as an industry over the last 10 years. Some estimates have the global direct-to-consumer genetic testing market reaching $2.5 billion by the year 2025. So. Much. Money to be made!

And these companies know it. From Father’s Day to the upcoming holiday season, it’s rare to go an hour without being inundated by companies like 23andMe and, offering their best deal ever to provide you a crystal ball that can answer all of your lingering questions about yourself. But before you rush off to by that spit kit as a gift for a loved one (or yourself), here are some important things to consider:


  • If you’ve done a DTC genetic test, then that means that a company has your entire genetic code, and you better believe they plan on sharing it. Sure, they tell you that they’ll only allow your genetic information to be used for the betterment of science. They leave out that they’re making some serious money off of you. And that the companies they sell your data to don’t always have the most noble of endeavors
  • Well, even if someone happens to get a hold of your genetic code, the company that did your testing said that it would be de-identified. So there’s no way anyone could know it’s you, right? Think again. Although DNA is ‘de-identified’ there have been many instances where re-identification is not only possible, but can be done rapidly and inexpensively (see here, here, and here).
  • Even if you change your mind and don’t want your genetic information to be in some company’s database somewhere, previous efforts have shown that it’s nearly impossible to put that cat back in the bag.


  • DTC genetic tests are designed to only look at select parts of your DNA – they are not comprehensive or examining every letter of your genetic code. This results in an immense amount of your genetics not being taken into consideration. So, at best, you’re only getting part of the picture. These partial results are also often misunderstood by patients who believe they’ve had more comprehensive testing done.
  • Just because you test ‘negative’ for a health condition on a DTC test doesn’t mean that you have a low risk for that disease. 23andMe currently tests for three gene variants in the BRCA1 and BRCA2 genes that are substantially more common in individuals of Ashkenazi Jewish ancestry. If you are not Ashkenazi Jewish and you carry a BRCA variant that increases your chance for cancer, the 23andMe test most likely will not detect it. These concepts can be difficult to understand, which is where meeting with a specialist (such as a genetic counselor) can be helpful.
  • On the flip side, just because you carry a gene variant for a health condition doesn’t necessarily mean that you will develop that disease. There is a specific variant in the APOE gene (APOE4) that has been linked to an increased risk for early-onset Alzheimer’s disease. However, the majority of people who carry one of these variants will NOT go on to develop Alzheimer’s disease. Furthermore, even if someone discovers they may have an increased risk for Alzheimer’s, there is currently no available treatment, which would lead to stress or anxiety.
  • Much of the genetic research that has been done thus far has been done on individuals of European ancestry. So, unless you’re extremely white, there’s a good chance DTC testing won’t be as accurate for you.
  • Labs that do DTC testing are also not as closely regulated, as evidenced by a story from a reporter who submitted a sample from their Golden Retriever to a DTC company, Orig3n, and not only did the lab not identify that the sample was not human, but a full report was issued.
  • Because of how complex interpreting genetic test results can be, the American Medical Association encouraged ‘patients to undergo genetic testing under the guidance of a physician or genetic counselor’.

Let’s say you’re not doing DTC testing for health reasons – then none of this applies to you, right? Check this out:

  • One science reporter documented how he took nine different commercial DNA tests for ancestry and got six different results, illustrating that each lab uses a different algorithm that influences the interpretation of results.

Unexpected findings

  • Many people who do the at home genetic tests are finding out that one or both of their parents are not who they thought they were (called non-paternity). Some studies have shown that non-paternity rates range from as low as 1% up to as high as 30%. This can understandably cause much stress and anxiety not only for the individual but for their family. With millions of people doing ancestry testing every year, that adds up to quite a lot of people who will fall into this category. In fact, it’s already happening frequently enough to have its own Facebook group.
  • There have also been instances of individuals who are adopted that track down their biological parents who did not wish to be found. And the cases where someone actually finds out they’re adopted from a DTC test.

Yes, genetic testing can provide powerful information – when the right test is used and a specialist, such as a genetic counselor, can help put that information into the context of your personal and family history. But there are limits to what any genetic test can tell you. Our genetics make us up, but we are so much more than our genetics.

Whether or not you decide to buy a DTC test this year, if you have questions about genetic testing or results from a DTC test that you would like to review with a genetics professional, please don’t hesitate to contact us

More reading: Genetics Home Reference (part of the National Institute of Health and the US National Library of Medicine).