The 19-year-old began to notice changes in his mother’s behavior around the start of the coronavirus quarantine. She had always been a nervous woman: She stopped flying after 9/11 and had hovered closely to Sam and his two younger siblings for their entire lives. But during the pandemic, his mom’s fears spiraled from quirky to deranged. It has turned her into someone he hardly recognizes. Though she didn’t used to be very political, she now thinks Biden is a pedophile who stole the election. She’s scared of radiation from the 5G towers in her neighborhood and, as a white woman,...