IVF clinics have long tested embryos for genetic disorders and abnormalities — but in recent years, new startups have been pushing the envelope of genetic testing, helping parents screen their future children for all kinds of health risks, ranging from diabetes to breast cancer.

Many people see this technology as promising — it can give parents, many of whom have already faced devastating losses, their best shot at having happy, healthy children. But others see a dark side to the advancing field of embryo screening. What happens when testing goes beyond health and parents get the chance to select for other traits, like eye color, height, or intelligence? What does it mean to want “the best” for your child?

On this episode, we look at new and emerging DNA technologies aimed at selecting embryos. We discuss critics’ fears, concerns, and the ethics of embryo screening. We also hear about one experiment from the past that went very wrong.

Also heard on this week’s episode: