Just open your mouth, collect some saliva and unlock a treasure chest of family secrets.

That’s the promise of direct-to-consumer genetic testing for ancestry. Genealogy services like Ancestry.com and MyHeritage offer consumers previously unknown clues about the origin of their ancestors, with many learning that their cultural backgrounds might be broader than once believed. These services also claim to pinpoint branches of family trees and reveal long-lost relatives.

The Appeal of DNA Testing

With only a saliva sample, services give customers a readout of about 1 million measurements of their individual genomes. The appeal and wide availability of such diagnostic technology has spurred consumers to also use their saliva to learn hidden clues about their health and genetic dispositions — it’s not just about learning where you come from, it’s also about where your health might take you.

Subject to Skepticism

The simplicity of genetic ancestry tests and their potential for shedding light on family history are boosting sales: more than 12 million people have used the home kits, according to MIT Technology Review. The testing, however, is subject to skepticism.

Sheldon Krimsky, a Tufts University adjunct professor in public health and community medicine, recently told TuftsNow that the methodologies of genealogy services haven’t been independently validated. Furthermore, these diagnostic technology offerings sometimes forward different ancestry results to the same person.

The Hurdles Behind Genetic Testing

Direct-to-consumer genetic health testing by services like 23andMe, Gene by Gene, MyMedLab and others carries the potential of risks and mistakes. Whereas an ancestry test might lead a consumer to mistakenly believe he’s part Finnish instead of Swedish, the ramifications of a misstep in health testing can be enormous.

For one, consumers receive testing results from many of these services without the counsel of a medical professional. This prompted the American College of Medical Genetics and Genomics to call for trained geneticists to explain the “‘increasingly complex'” results that typically have to be placed in context with medical and family history.

Direct-to-consumer genetic testing for health is designed to detect variations in genes to assess an individual’s level of risk for a disease, but it can’t guarantee with any kind of certainty that a person will get the disease, according to the Cancer Treatment Centers of America. Not every disease is caused by genetics; environmental and lifestyle factors can also factor as triggers.

Despite these known uncertainties, medical experts believe consumers will make crucial health and lifestyle decisions without proper medical advice, and overlook the overriding concern that these results may be wrong.

From Ancestry to Improved Health

Even with the many caveats of the take-home tests, genetic health testing has the potential to improve health care. Consumers who seek professional medical advice about their genomic test results can make informed lifestyle choices that could prevent disease. Even if the results are flawed, at least a conversation about an individual’s health has begun.

Most of the DNA testing services intend to keep consumers’ personal data long after they’ve received their results — which concerns privacy advocates — but consumers are free to share results with their physicians.

But perhaps the biggest benefit from this testing might be the opening of the floodgates on genomic data, leading to a better understanding of how genetics works.

Is it Worth the Risk?

Genetic testing, even when conducted by reputable research facilities, is full of probabilities and variables, in large part because each set of DNA has variations, many of which are rare, and are thus uninterpretable to science. As a Columbia University bioethicist told The Atlantic, a genetic test is “‘like a weather report.'”

But several data banks — including the National Institutes of Health’s Genetic Testing Registry — are collecting genetic test results from direct-to-consumer services, doctors and other sources to further genetic research and illuminate the workings of genes.

A consumer trend that started as a quest to understand one’s heritage could ultimately lead to science’s understanding of the human body.