Sit down America, and let’s talk about making babies. Specifically, designer babies. Because ever since in vitro fertilization made it possible for parents to select embryos with the best genetics, precisely-engineered progeny have been a big fear. And now that a powerful gene-editing technique has been used on human embryos, it’s fine to get a little freaked out. But—here’s the important bit—let’s not leave out the hope of eradicating thousands of diseases, and the potential to make many pharmacological treatments obsolete.