“A lot of times these tests are based on associations, not randomized, controlled trials looking for causal effect,” MacKay said. “For example, watermelon consumption is associated with drowning — because more people swim in the same season as they eat watermelons. But that’s just an association.”

The advice companies give based on your test results is often vague or standard, too. Caulfield’s results indicated he was at risk for certain cardiovascular problems and cancers.

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Others fear it could do more harm than good.

Last week, police arrested Kevin Charles Queau, 42, accused of killing 24-year-old Crystal Saunders in 2007, thanks to advancements in DNA technology in 2014 that helped the Canadian DNA databank link him to a DNA sample found on the woman’s body.

Arthur Schafer, an ethics professor at the University of Manitoba, says Queau’s arrest shows the national DNA databank can be “really useful in a number of cases,” but warns “without rules or regulations, there could also be serious harm.”

The RCMP stewards the databank, established in 2000, which holds just over 650,000 DNA samples from crime scenes, as well as profiles of people convicted of certain designated offences, victims of crime, unidentified human remains, volunteers and missing persons and their family members from across Canada.

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