Spit in a tube, and we’ll tell you your past — and, perhaps, your future.

That’s the pitch behind many of the direct-to-consumer DNA tests on the market today, which offer to trace your ancestry and spot any genetic mutations that put you at risk for cancer.

But what many of these testers don’t tell you is how much they want your DNA — and how much your $130 test is actually worth to them.

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“Very few of these genetic tests can be run as cheaply as they’re being offered to consumers,” said Malia Fullerton, a professor of bioethics and humanities at the University of Washington. “The way you make your money is by repurposing the data.”

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Your DNA has become a commodity in itself, and ancestry companies are storing it in databases that can be used to develop expensive new drugs, study hereditary diseases, increase insurance premiums or even track down potential criminals.

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Some companies have stricter privacy rules than others, but Fullerton says one DNA test could come back to haunt you — or one of your relatives — years down the line.

“Even if you’re willing to take the risk and make your information available … you are dragging along your family members,” Fullerton said.

Here’s what you need to know about the race to cash in on the most intimate piece of personal information you have: your DNA.

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What’s in my DNA?

Your DNA is a genetic blueprint for your whole body — from your height and ethnicity to your blood type and risk of hereditary diseases. It’s in all of your cells and it can hold tens of thousands of genes that define who you are.

Scientists created the first full map of a person’s DNA in 2003 at a cost of US$2.7 billion. Nowadays, it only costs about $1,200 to sequence a full human genome or a few hundred dollars to scan parts of the genome, depending on the complexity of the scan.

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This affordability has triggered a booming DNA-testing industry dedicated to helping you find long-lost relatives and ancestral ties to faraway countries. Newer tests can also spot mutations that put you at risk of developing cancer or identify genes that respond well to certain drugs.

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You can collect your own DNA for one of these tests by scraping the inside of your cheek with a cotton swab. It doesn’t hurt, and you certainly won’t miss the DNA in your spit. However, that information can be harmful if it falls into the wrong hands.

Who is banking DNA?

Experts say we’re in the midst of a DNA gold rush as public researchers and private firms race to build their own massive research databases. They want to create a sort of genetic search engine so they can “google” various genes linked to hereditary diseases, aging or drug interactions. However, these databases are only as valuable as the samples they contain — and more samples mean more money for private companies.

AncestryDNA is currently sharing its database of 14 million customers with a Google subsidiary for longevity research. The company 23andMe has a deal with GlaxoSmithKline, a major pharmaceutical company, to develop “novel treatments and cures based on genetic insights from the consented 23andMe community.” The company says approximately eight million of its 10 million customers have opted into its research program.

The rest of the DNA-testing companies are flirting with one million customers, and they tend to share their data more widely.

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“When you give your genetic information to one of these direct-to-consumer companies, they generally keep it,” said Tim Caulfield, a professor of law at the University of Alberta and Canada Research Chair in health law and policy.

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Caulfield says you should always read the fine print on direct-to-consumer DNA tests because companies will tell you if they plan to share your data with others. DNA-testing firms are required by law to disclose this up front, but you probably won’t know exactly what’s happening unless you read their terms of service.

“Make sure you know what you’re getting involved in,” Caulfield told Global News. Tweet This

He adds that your DNA can be used against you in a variety of ways. For example, an insurance company might want to boost your premiums if you have a mutation linked breast cancer, and the FBI might want to check your DNA against its cold-case database, just to see if you’re a partial match.

Investigators found the suspected Golden State Killer by uploading his old DNA sample to GEDmatch, an open-source DNA database, in 2018. They found a partial match with one of his relatives and managed to track him down through process of elimination.

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AncestryDNA and 23andMe both say they don’t share their data with law enforcement unless they are subpoenaed to do so. However, some of their competitors, including FamilyTreeDNA, have started collaborating with law enforcement.

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Canada has made it illegal for employers or insurance companies to discriminate based on genetic data, such as a predisposition toward cancer. However, the science often moves faster than the law can keep up, Caulfield says. The situation also becomes more complicated when you’re sending your DNA to another country where different laws apply.

“I think we need more of a regulatory response in Canada,” Caulfield said.

Private profit ahead of public research

AncestryDNA and 23andMe are the two largest testing companies by far, and they’re sitting on massive amounts of data that the scientific community would love to see. For example, cancer researchers are trying to build their own databases to search for rare genes linked to certain forms of the disease, but they’re working with tens of thousands of samples, not millions.

“You have to pool your data together to understand the bigger picture,” said Dr. Lillian Siu, an oncologist at the Princess Margaret Cancer Centre in Toronto. Siu says private companies are holding onto tremendously helpful information that could push cancer research forward if it were shared more widely.

“This is the only way we can learn,” she told Global News. “If we silo our data, we will only see what we have. We will never see the world.”

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Siu asks her patients to contribute to Project GENIE, a gene-sharing database run by the American Association for Cancer Research. The database includes over 60,000 voluntary patient records from more than a dozen organizations in Canada and the United States.

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“We can use that data to learn,” Siu said. “I often use the GENIE data set, for example, to understand the frequency of a mutation.”

However, some genes are one in a million, meaning a database of 60,000 might not have enough samples for a proper study.

Several national health organizations have established similar biobanks. The U.K. Biobank is one of the largest public databases with info from 500,000 volunteers. However, these databases are all dwarfed by the ones run by AncestryDNA and 23andMe.

“The data that is sitting with them is extremely useful for us as well,” Siu said. “They should not hesitate about sharing.”

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Genealogy enthusiast Leah Larkin says ancestry companies are doing a lot of good with their data. She says they help reunite families and give pharmaceutical companies the tools they need to create new life-saving treatments.

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“There is a huge upside to all of this DNA testing,” Larkin told Global News. “For them, a large database means they have sufficient power to search for … genes associated with medical conditions.”

However, she also acknowledges that these companies pose a risk to personal privacy, both for their customers and their customers’ families.

“No one can guarantee that anything on the internet is never going to get hacked,” she said.

“If you want absolute privacy, I would say don’t do a test,” Larkin said. Tweet This

Caulfield says the benefits of getting a DNA test often don’t outweigh the risks, particularly when it comes to getting screened for cancer.

“There is a huge amount of variability between these direct-to-consumer testing companies,” he said.

“People should view it as recreational science and go in with a skeptical eye.”