The Dangers of Do-It-Yourself DNA Testing

At this point, the parents-to-be have to worry that their kid will have a mutation associated with an incurable disease. If he has it, they also have to fret that he has anywhere from a one in five to a four in five chance of actually contracting the disease. Really, how helpful are these numbers? That's a big range of probabilities. I wager it doesn't feel terribly good to be tracking the genetic lottery of your son's health, disease by disease.  In fact, I imagine that it's downright harrowing.

Dr. Alan Guttmacher, acting director of the National Human Genome Research Institute of the National Institutes of Health, agrees. In September, he told the New York Times that "[DNA testing] can be neat and fun, but it can also have deep psychological implications" because it can profoundly influence the way we view ourselves, our loved ones, and our relationship to the world. As Guttmacher told Time, "a little knowledge is a dangerous thing."

Here Guttmacher isn't just talking about the strange helplessness of knowing the ever-so-approximate probability of your child getting sick. He's also speaking to the fact that DNA tests themselves only provide a little knowledge -- just one small piece of the complex puzzle that is our health. Unfortunately, DNA tests often promise much more than this. One company, Navigenics, is actually dedicated to reading your DNA and diagnosing you with a set of medical risk factors that you then discuss with an appointed "genetic counselor." The idea is that genetic tests reveal some sort of fundamental physiological truth; a complete and comprehensive assessment of our health.

It's true that some conditions, like cystic fibrosis and Huntington's disease, have been scientifically proven to be associated with particular genetic mutations. But many other conditions have not been shown to have a genetic origin -- particularly when that gene is detected without an intimate understanding of environmental factors surrounding a patient, as it is the case when researchers on the other side of the country analyze your spit.