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DNA testing kits: Everything you need to know about testing your DNA at home

DNA Testing
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Home DNA testing kits are changing the way people see themselves, and their increasing availability, decreasing prices, and variety of choices allow us to discover the secrets behind our genetics: where we're from, who our ancestors are, and even which diseases we may be susceptible to. We reviewed kits and found the best DNA testing kits you can buy, but how do they work? Here's what you need to know about DNA testing kits. 

Why buy a home DNA testing kit? Here's what you can find out

Home DNA testing kits should only be used for informational purposes: they cannot diagnose any ailments or tell you with 100% certainty where your ancestors came from. With that in mind, it may seem hard to find a reason why you should invest in a home DNA testing kit. 

However, there is a myriad of reasons why these kits can be handy tools. The first couple of reasons are easy to pin down: they can shed light on where you come from, geographically, and how your ancestors traveled across the globe; they can tell you more about your body on a cellular level, and because there will always be at least one interesting piece of information that will surprise you! Other reasons include:

Finding long-lost family members: Some DNA test kit sites compare your DNA to others' in their database, and draw conclusions based on the similarities between your genetic makeup. Some people have found secret siblings, long-lost biological parents, and first, second, and third cousins using DNA test kits. 

Optimizing your habits for better health: Many home DNA testing services analyze your DNA and determine your likelihood of having some features, like the color of your hair or the color of your eyes. But they go deeper, telling you about your muscle composition and your diet needs to maintain a healthy weight. 

Participating in genetics research: While this may not be a primary driver to purchase a home DNA testing kit, some people are intrigued by the ability to participate in important research in genetics. This research can help enable genetic discoveries and even provide information that leads to developing new drug therapies. 

Discovering more about your ancestors: You may know where you're from and where your parents are from, but many DNA testing kit services will show you a more granular view of your ancestors' migration. For example, you can trace the migrations of your maternal line based on your haplogroup. 

How much does a home DNA test cost?

Most ancestry DNA kits cost about $100. AncestryDNA and 23andMe's Ancestry test fall nicely into that price point. If you’re looking for a bargain, we recommend waiting to buy until your preferred test is on sale, as they’re often available well below their usual price. To get the most for your money, buy an Ancestry or 23andMe kit on sale, and then upload your raw data to MyHeritage DNA’s database, which is free. 

How to take a home DNA test

The DNA tests we reviewed either require a saliva or cheek cell sample. Saliva-collecting kits include a tube that’s marked with a fill line and sample number. The tube often has a liquid-filled cap with a stabilizer that acts as a preservative to protect your DNA from degradation during transport. 

Cheek swab sample kits include one or two swabs for scraping the insides of your cheeks for 30 seconds to a minute to collect cheek cells and some sort of container to place the used swabs into after collection. This prevents contamination. 

Our testers found upsides to both types of kits but generally preferred saliva collection kits, even though they took longer.

The trick for collecting a saliva sample is to give yourself plenty of time to create enough spit to fill your tube to the fill line (not including any bubbles). You should not eat or drink anything for at least an hour before collecting your sample, so it’s best to plan to collect your sample before eating. 

Our testers collected samples before lunch and found that thinking about the upcoming meal made saliva production easier, particularly as we collected multiple samples. Planning ahead and making sure you stay hydrated before you collect a saliva sample helps as well.

To prepare to take a cheek-swab sample, you also have to refrain from eating for about an hour before. Swab kits generally contain more components, including one or two swabs and containers to protect the used swabs from contamination. 

We found it easiest to organize all the pieces first, to prevent any fumbling with a sample collection swab in hand. Some cheek cell kits put a stabilizing liquid in the sample containers, which required extra caution to prevent spilling.

DNA testing kits and law enforcement

There are mixed reactions to the use of ancestry DNA databases in criminal cases. On one hand, the rise of readily-available DNA information for millions of people has led to the arrests of several suspects related to long-cold cases, including the recent arrest of the Golden State Killer. 

On the other hand, law enforcement accessing private databases of genetic information from consumers raises several questions regarding privacy and ethical issues.

Of course, most DNA used by law enforcement in the U.S. does not come from direct-to-consumer DNA tests. The federal government and many states collect DNA samples from suspects of violent crimes after arrest or due to probable cause. These samples are added to the Combined DNA Index System, or CODIS, which is a national database for forensic information.

Following a recent case in Phoenix, in which a patient who had been in a coma for nine years gave birth, Arizona lawmaker David Livingston sponsored a senate bill that would require certain occupations to submit DNA samples along with fingerprints for use by law enforcement. 

Though Senate Bill 1475 has been updated since its initial draft, it could set a precedent that normalizes collection of DNA samples from everyone, not just those suspected or charged with a violent crime. 

Should I buy a home DNA testing kit?

Direct-to-consumer DNA tests are still relatively new. The first ancestral DNA test launched in 2001 by FamilyTreeDNA, but companies didn’t start genotyping autosomal DNA until 2007. 

Still, tests and results have come a long way since then, with much lower prices and streamlined sample collection, registration and results. If you’re still on the fence about whether or not to buy a DNA ancestry test for yourself or as a gift, here are a few things to consider. 

DNA tests offer a wealth of insights into your connections to family, history and geographical locations. They both entertain and encourage you to dig into what you know about yourself. 

The tests make great gifts to bring you closer to your family and involve you and your family in the development of a cutting-edge science at the same time. Beyond that, the information is extremely useful for adoptees, people looking for lost relatives, genealogists and for medical science. 

Many DNA databases, including Ancestry, 23andMe and MyHeritage DNA, have family search features, which match your DNA with that of potential relatives. These features help users searching for family, including adoptees and children conceived through sperm donations. 

Almost every DNA testing service we interviewed for this article had a story ready about how its service facilitated a heartwarming family reunion. Like these from Ancestry, this one from MyHeritage and this one from 23andMe. Because many DNA services also have resources like family-tree builders, the tests work in tandem with genealogical research.

For better ancestry and medical insights, you should encourage family members, especially parents and grandparents, to take a DNA test as well. If your family is from a specific geographical location for generations, your samples could potentially improve the service's reference panel, in turn improving results for everyone. 

If you’re female and take a test from 23andMe or LivingDNA, you can view paternal haplogroup information, and you get more information when one of your male family members takes a test as well.

Home DNA tests: Not all results are welcome

Most direct-to-consumer DNA test companies warn that the tests may reveal things you wish you didn’t know about your family. For example, you could find out that one of the people who raised you isn’t your biological parent or that there’s an entire branch of your family you didn’t know about. There isn’t a way to prepare for a shock like that, but you can opt out of a company’s family-matching services if you’d rather not know.

You might want to stay away from DNA tests if you or any of your close relatives have committed a crime. Although ancestry DNA testing companies don’t typically share database information with law enforcement, consumer DNA tests may result in future identification. 

For example, FamilyTreeDNA, which has a database of close to a million samples, has agreed to give the FBI limited access to the company's DNA database. This access consists mainly of consumer-level insights, like matches with other members of the FamilyTreeDNA community who have enabled family matching; by law, however, more in-depth investigation requires a subpoena.

Many people who submit their DNA to a direct-to-consumer company also upload their raw information to public databases like GEDmatch, which law enforcement can access. People upload their raw DNA data after taking another test, like those from 23andMe or Ancestry, to several open online DNA databases. Most companies do not release database information to law enforcement. However, a recent study found that, using publicly available data, it's possible to identify up to 60 percent of Americans with European heritage via third-cousin-or-closer DNA.

Although FamilyTreeDNA is the only DNA testing company openly working with law enforcement, other DNA companies don’t necessarily keep your DNA information private. Many direct-to-consumer DNA testing companies sell your data to third parties. For example, 23andMe shares customer data with pharmaceutical giant GlaxoSmithKline, which uses the information to develop medical treatments. In this case, you can opt out of having your DNA information used for research, and the data is shared only in aggregate.