The Nobel-winning biologist has drawn global criticism with unfounded pronouncements on genetics, race and intelligence. He still thinks he’s right, a new documentary finds. It has been more than a decade since James D. Watson, a founder of modern genetics, landed in a kind of professional exile by suggesting that black people are intrinsically less intelligent than whites. In 2007, Dr. Watson, who shared a 1962 Nobel Prize for describing the double-helix structure of DNA, told a British journalist that he was “inherently gloomy about the prospect of Africa” because “all our social policies are based on the fact that...