It’s that time of year again, when kids and adults make their wish lists, usually for things they want, rather than what they need. As adults, we might want to check our own wish list twice. In getting what we want, we may also receive an unpleasant surprise. It’s what we call the ‘law of unintended consequences.’

Although it was first used in economics,[1] the law of unintended consequences has become a shorthand way of saying that when you try to solve one problem, you might create another one that’s even worse. Or, in the pursuit of one goal, you may end up getting a result that you didn’t foresee.

The pursuit of knowledge can be one of those goals with unintended consequences. We are designed to be curious. We live in a fascinating universe, after all. And one of the things we are the most curious about is ourselves. Think of all the self-evaluation questionnaires there are, ranging from your personality type to your learning style to your nutritional profile.

Knowledge needs a context, and scientific knowledge needs interpretation. In the Google age, each person might think they are an expert because they can find information. But how do we decide if the information we Googled is credible, or what to do with it?

23andMe is a company that offers a do-it-yourself DNA test kit to help you find out if you carry a disease, if you have genetic health risks, and how you might respond to certain medications. It also reveals your genetic lineage. Some people might want to find out if they’re related to someone famous, or request a paternity test.

Last year, a woman and her older brother went to 23andMe to find out if they shared the family predisposition for cancer and bipolar disorder. The test results  didn’t show anything surprising. But, the woman also wanted to see if she had any “close relatives,” despite the warning that genetic information is irrevocable, and could be emotionally distressing. She learned that her brother was her half-brother, and that she was the result of a one-night stand.[2] Now there’s an unintended consequence that can shake your world.

Our desire for knowledge can also lead us to ignore basic guidelines for medical data. Few of us are qualified to interpret our genomic profile, which should be done by a professional genetics counselor. Nor are we qualified to judge the reliability of the tests. 23andMe was ordered by the FDA to stop marketing the tests, in part because they have failed to provide any studies or data to show that the tests actually work.[3]

The do-it-yourself DNA test may seem like harmless entertainment. But, the unintended consequences of getting that knowledge may lead you to fear getting a serious genetic disease, without even knowing the likelihood. Or, finding out some family history you’d have been better off not knowing.

So, if knowing more about yourself is on your wish list this year, check it twice...then maybe ask for something else.

[1] Rob Norton, “Unintended Consequences,” The Concise Encyclopedia of Economics (2nd ed.). http://www.econlib.org/library/Enc/UnintendedConsequences.html.

[2] Daniel Engber, “Who’s Your Daddy?” Slate.com, May 21, 2013. http://www.slate.com/articles/health_and_science/science/2013/05/paternity_testing_personal_genomics_companies_will_reveal_dna_secrets.single.html

[3] Amanda Holpuch, “FDA Orders Company 23andMe to Cease Marketing of Screening Service,” The Guardian, November 25, 2013. http://www.theguardian.com/science/2013/nov/25/genetics-23andme-fda-marketing-pgs-screening.