By Adam Piore, Newsweek, March 2, 2020 In the mid-2000s, Dr. Nadine Burke Harris opened a children's medical clinic in the Bayview section of San Francisco, one of the city's poorest neighborhoods. She quickly began to suspect something was making many of her young patients sick. She noticed the first clues in the unusually large population of kids referred to her clinic for symptoms associated with attention deficit hyperactivity disorder—an inability to focus, impulsivity, extreme...