The catch, though, is that as the accuracy of these tests continues to improve, they will be able to detect a greater range of genetic variations, including some with murkier implications. For example, rather than indicating something with certainty, they could reveal elevated risks for certain diseases or disorders. These advances could collide with the politics of abortion and raise the ugly specter of eugenics. When, if ever, should parents terminate pregnancies on the basis of genetic results? Do we have the wisdom to direct our own evolution? And perhaps most important, are there limits to how much data parents should have—or want to have—about their children before birth?