Have you seen the commercials for those companies that say they can tell you what parts of the world your ancestors are from just by looking at your DNA? Many of the tests involve sending in a tube of spit that will later be analyzed by the company.

The commercials sound so factual and interesting. People claim that they had no idea they were from a certain part of the world. It can make you curious if you really know where your family is from or not.

The information in the commercials and on the websites where you would order the tests looks so scientific and sounds like it’s 100% accurate. Many people assume that the results they get back will tell them without a doubt where their ancestors used to live.

Before you spring for one of these tests, you deserve to know the truth.

Identical twin sisters decided to put five popular DNA tests to the test. They both took the following tests: Ancestry DNA, 23andMe, Living DNA, MyHeritage DNA, and FamilyTree DNA.

Considering that they’re identical twins, we would assume that their results would be identical. We would also assume that their results from each company would be identical or at least very, very similar.

That’s not what happened. The twins were shocked that not only did they receive different results from different companies, they received different results from each other. They were left feeling more confused about their ancestry than they were before they even took the tests.

They decided to dig in deeper to see if there was a rational explanation for why tests that are advertised as being so accurate could have such different results.

According to Simon Gravelle Ph.D., a Population Geneticist at McGill University in Montreal, Canada, these tests are not 100% accurate. “It is a statistical guess. It’s an informed guess.”

Really? A guess? How can DNA be a guess?

Timothy Caulfield, a Health Policy Professor at the University of Alberta, says, “Don’t take it too seriously, but know that you’re just getting some information that’s an approximation of how your DNA compares to other people. It’s not tracing back your heritage.”

The commercials certainly make it look like they’re tracing back your heritage. Turns out, they’re not. They’re simply comparing a small part of your DNA to the DNA of other people and making an informed guess about where your ancestors are from. Not only that, but your results can change over time as the companies update their databases.

That doesn’t sound accurate at all. Caulfield warns that the message these companies are sending to the consumers is “misleading.” He adds, “I think they’re selling something that isn’t really supported by the science.”

If you decide to take one of these DNA tests and are surprised by the results you get, don’t change your whole world view or feel the need to embrace a new culture. Chances are, the results are inaccurate.

See just how different the results were for these twins in the video below.

Have you taken any DNA tests to try to learn about your heritage? Does it surprise you to learn that the results aren’t actually facts but informed guesses?