With Genetic Testing, How Much Information Is Too Much?

In the first hours after my daughter was born, three years ago now, I searched her for answers. I examined her ears, looking for the telltale shape associated with certain genetic syndromes. I inspected her mouth for a cleft palate. I watched her movements and wondered what they might reveal.

I don’t know what I would have said if, in those days in the hospital, I had been offered the chance to search her genome for predisposition to disease. But this may soon be reality. As genetic testing has become cheaper and more widespread, scientists around the globe are aiming to sequence tens of thousands of infants to study the feasibility of offering this type of testing to millions of babies at birth. This future is closer than we think, and I believe that we should embrace it — which means we need to be honest about how much work there is still to do.

Shortly after birth, almost all newborns have their heels pricked, and the resulting blood is tested for a few dozen serious conditions for which early...