Tests are a standard part of modern medicine. We willingly screen our blood, urine, vision, and hearing, and submit to a host of other exams with names so complicated that we can only refer to them by their initials: PET, ECG, CT, and MRI. Genetic tests of our risks for disease are the latest trend in medicine, touted as an approach to informed and targeted treatment. They offer hope for some, but also raise medical, ethical, and psychological concerns for many including when genetic information is worth having.

To Test or Not to Test arms readers with questions that should be considered...