Survivors of the Chernobyl nuclear disaster have long lived with a lingering fear: Did radiation exposure mutate their sperm and eggs, possibly dooming their children to genetic diseases? “Many people think if you have been irradiated, you must have effects in the next generation,” says immunologist Dimitry Bazyka, director-general of the National Research Centre for Radiation Medicine in Kyiv, Ukraine. But new findings from Bazyka and his colleagues should dispel that fear. In a study of more than 200 Chernobyl survivors and their children, the researchers found no evidence of a transgenerational effect.