Radical beliefs and violent hatred are back in the headlines and worrying policymakers around the world. This column discusses new research that suggests that, in the case of Nazi Germany, subjecting an entire population to the full power of a totalitarian state was extremely effective in instilling lasting hatred. Extremist views are still three times higher among Germans born in the 1930s than those born after 1950. However, family and the social environment can isolate young minds from the effects of indoctrination at least to some extent.