Spit decisions: DIY tests endanger DNA data

Although direct to consumer DNA tests might seem like a harmless way to connect with lost relatives and find out about your ancestry, you'll only ever have one set of genes and once that data is out there it's very hard to get it back.

As the cost of sequencing the human genome has rapidly fallen, DNA services such as 23andMe and Ancestry have quickly risen in popularity, allowing easy access to your genome with just a bit of saliva in a tube.

These companies usually offer two things: to identify specific gene markers which give you details about your health (such as the gene for celiac disease or lactose intolerance), and to match your DNA to a database which compares it to DNA of other people of a known ancestry. The tests are not always accurate in either case, and any information gained from them should be taken with a grain of salt.

But that's just the start of your problems. Once your DNA is sequenced and you get the results, that data doesn't remain with the provider of the tests. Many of these companies sell the de-identified data to drugmakers and scientists, and it's difficult to later delete the results off your account (although it can be done in certain circumstances). Many providers also have the right to keep your saliva frozen for many years after the test. 

Even if you've never taken a DNA test you could still be at risk, as your actual DNA doesn't need to be in a database for you to be identified — if a family member has done a test, you're out of luck. A study late last year found that white Americans have a 60 per cent chance that a relative has added their DNA to a database — which is then able to be used to identify them. 

Between 2007 and 2017 it's estimated that 12 million people took a consumer DNA test. But 7 million of those people took the test in 2017. This has only expanded in the last two years — when I contacted 23andMe they explained they have sold 10 million kits to date.