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At the start of this decade, the federal government called out consumer DNA testing as a burgeoning scam industry. Little did we know how it would explode in popularity. 

In 2010, the U.S. Government Accountability Office (GAO) published an investigative report that bashed consumer DNA test companies for misleading the public. It accused them of deceptively claiming their products could predict the odds of developing more than a dozen medical conditions; some even went as far to offer equally dubious dietary supplements. The report had followed a similar lambasting of the industry by the GAO in 2006. 

Also in 2010, the FDA publicly warned 23andMe and other companies that genetic health tests were considered medical devices and needed to be cleared by the FDA before they could be sold to the public. Three years later, following a lack of response from 23andMe, the agency took the harsh step of temporarily banning 23andMe from selling its health-related tests at all.

Despite these hurdles, the DNA testing industry has nonetheless exploded. According to a report by MIT Technology Review this February, more than 26 million people have had their DNA tested by the biggest names in the industry, with AncestryDNA, 23andMe, and MyHeritage being the top three. 

Consumer DNA testing is undoubtedly now mainstream—but it’s not much less scammy than it was when the decade started.

The industry has existed since the late 1990s. But in 2007, the new kid on the block, 23andMe, became the first company to offer a particular kind of at-home DNA test that was cheap, easy to use, and promised to track back your origins further back than ever before.

23andMe’s tests—and eventually those of its competitors—search for and analyze the most common genetic variations, called single nucleotide polymorphisms (SNPs), in our autosomal DNA, the 22 of 23 pairs of chromosomes not used to determine sex. For as little as $99 and a spit sample, these SNP-based tests are advertised to determine a person’s ancestry or genetic health risks. But much of this realm of consumer DNA testing, as the GAO report showed, can uncharitably be described as complete bullshit.

The crux of the problem is that our genetics are only a piece of the puzzle that influences our health. Sure, you can sometimes point to a specific gene mutation that always makes someone sick in a specific way if they carry it. But much more often, it’s a complex, barely understood mix of gene variants that predispose us to develop cancer or heart disease—and that risk can be amplified or muted by our environment (including the crucial months we spend in the womb).

In the earliest days, companies didn’t much care for this complexity, using weak evidence to make sweeping health claims about which genes ought to make you more of a fish eater or develop diabetes.

Following the FDA’s ban in 2013, 23andMe spent the next two years devising genetic health tests that wouldn’t overpromise. In 2015, it was allowed to sell tests that told people if they carried a recessive mutation for genetic conditions like Bloom syndrome and sickle-cell disease. A positive test meant their children would have a 25 percent chance of having the condition if both parents were carriers. Two years later, it became the first company with FDA-approved tests that were allowed to tell people about their risk of developing one of 10 diseases or conditions, such as late-onset Alzheimer’s or celiac disease.

23andMe’s return to the health side of things wasn’t the only fuse that lit a fire under the consumer DNA industry—the tens of millions in annual advertising now being spent by companies like MyAncestry certainly helped, too. But regardless, the FDA’s approval of these tests signaled a new opening in the industry. And unsurprisingly, the industry as a whole has ballooned, as has the glut of scammy services on offer.

Many of these companies now steer clear of making blanket health claims, but it doesn’t make them any less laughable. Your DNA results can apparently tell you whether you’ve found your romantic match, how to be good at soccer, and, like a decade ago, how to find the perfect diet and avoid bloating. Just don’t pay attention to the studies showing that there’s no consistent link between genes seemingly tied to our nutrition and any actual diet-related conditions.

It’s not only the tests vaguely connected to our health that are the problem. As Gizmodo once illustrated, even relying on these DNA tests to figure out your ancestry is a dicey proposition. At best, you’re roughly estimating where your recent ancestors lived, but that estimate can vary widely depending on which company does the testing, thanks to the different algorithms they use. And the farther away your lineage is from Europe, the less accurate these tests will be for you, thanks to the fact that the algorithms—as well as the research linking genes to our health—are largely based on the DNA of white Americans and Europeans.

Health and ancestry aside, sharing your DNA with the outside world can have unintended consequences. Law enforcement agencies are now using genealogy databases to solve criminal cases, by connecting anonymous crime scene DNA to DNA submitted to these family tree companies, working backward through distant relatives to identify their suspect. And while some people may be fine with this genetic sleuthing, there are no clear rules on how this data can be used by law enforcement—there’s merely the promise by private companies that they will share responsibly. This November, police in Florida obtained a warrant to search through a third-party genealogy database, months after the service had enforced a new opt-in policy meant to let users decide if they wanted their data to be searchable by police in these cases.

At a certain point, it won’t even matter whether you’ve decided to share your DNA. A study last October estimated that once enough people’s DNA is in a database—a scant 2 to 3 percent of any given population—anyone could conceivably track the identity of every person in that population using the same techniques genetic detectives are using now. And researchers have already demonstrated how less scrupulous forces, including hackers, could actively manipulate these databases.

None of this is meant to diminish the real potential of genetics as a field of research and medicine, nor the progress that has been made over the past decade.

Companies like 23andMe rely on detecting thousands of genetic markers —still only a tiny slice of our DNA. But the technology that allows a person’s entire genome to be sequenced has vastly improved, scaling down its costs and upkeep over the past decade. These techniques can scan a person’s whole genome as well as the smaller part of the genome that codes for the proteins our body’s cells make, called the exome.

In 2010, for instance, the company Illumina initially offered its whole genome sequencing at $50,000 a person; this year, Veritas dropped the price of its service to only $600 and says it may soon charge as little as $100.

These innovations have led to large-scale research projects that collect genetic data from hundreds of thousands of people at once. Scientists can scour through these large datasets to find new links between our genes, traits, and medical conditions. This research has helped us better understand longstanding questions about our biology and health. Someday soon, genetic sequencing may also help us optimize the existing medical treatments people get, particularly for conditions like cancer.

Right now, though, it’s still up in the air how useful this info dump really is to the average person looking to stay healthy.

In March, 23andMe debuted (or more accurately, reintroduced) a service that tells people about their genetic risk of type 2 diabetes. Unlike the tests approved by the FDA, it relies on what’s known as a polygenic risk score. This adds up the very small contribution of many genetic markers to a particular condition, which combined might be enough to nudge your overall risk upwards.

The trouble is that these markers have little to do with why you get type 2 diabetes—your age or weight play a much bigger role. And even if the test does consider you genetically unlucky (an average risk difference of 5 percent from a “typical” person), the advice you’ll get is the same that anyone hoping for a long, healthy life would get: eat more vegetables and exercise more. This test, as well as many of those offered by the hundreds of big and small DNA testing companies on the market, illustrates the uncertainty of personalized consumer genetics.

The bet that companies like 23andMe are making is that they can untangle this mess and translate their results back to people in a way that won’t cross the line into deceptive marketing while still convincing their customers they truly matter. Other companies have teamed up with outside labs and doctors to look over customers’ genes and have hired genetic counselors to go over their results, which might place them on safer legal and medical ground. But it still raises the question of whether people will benefit from the information they get. And because our knowledge of the relationship between genes and health is constantly changing, it’s very much possible the DNA test you take in 2020 will tell you a totally different story by 2030.

Given how popular at-home DNA testing has become, there’s really no sealing the genie back in the bottle. So if you want to get your genetic horoscope read this holiday, don’t let me stop you. But it’s a big decision you should sleep on. After all, once your DNA is out there, there’s no going back.

[Ed Cara is a science writer at Gizmodo. He can be reached at ed.cara@gizmodo.com or via twitter at EdCara4.]