VANCOUVER -- They arrive in the mail. A simple saliva test is all you need, and you send them off. Some DNA test kits just claim to be able to trace your ancestry, while others do a lot more than that.

Four years ago, Sara Altschule used a 23andMe DNA test kit, which also reveals markers for disease.

“I unfortunately got my test results back, which did show that I carry the BRCA2 mutation, which increases my risk of developing breast cancer by quite a bit and ovarian cancer,” Altschule said.

She ended up getting a preventative double mastectomy with reconstruction after her genetic counsellor confirmed the results. While Sara is grateful she took the test, she understands that a positive result could be a burden on other family members who might carry the mutation.

“Once you get your results, that probably means you need to inform people in your family that you either got it from one of your parents and that could affect your siblings, that could affect your cousins,” explained Altschule.

Some of the DNA tests can help to determine if you’re likely to develop diseases such as breast cancer or Alzheimer’s. However, they could also give you a false sense of relief or fear.

“While a positive result from these tests can mean you do have a higher risk of a certain disease, a negative result doesn’t necessarily mean you’re out of the woods, as there could be other variants that can cause that disease not detected by the test,” said Catherine Reports, Consumer Reports health editor.

23andMe says it clearly explains the limitations to users. While Altschule’s story is an example of how DIY tests can be helpful, some may find the results confusing, misleading or upsetting.

In a Consumer Reports survey, about 10 per cent of people who used these tests said their reports contained unsettling information, such as news that someone thought to be a biological relative wasn’t actually related to them at all.

If you think these kits are going to give you a complete picture of your health, you’re likely to be disappointed. There is also the possibility that the test results could reveal information you may not even want to know about your family.

Bottom line: A DIY DNA test kit might be right for you as long as you understand what your results may or may not signify.

You should also be aware that there are few laws that regulate what a company can do with your genetic data once they receive it, so it could be sold to a third party without you knowing it.

With files from Consumer Reports