Helen Gurley Brown, the author of “Sex and the Single Girl” (1962) and for three decades the editor of Cosmopolitan, was born in Green Forest, Ark., a tiny town in the Ozark Mountains. Her father died when she was 10; her sister had polio; her family was “hillbilly,” she wrote, and poor. Once she got out, she looked back only by force of will. She liked to quote a line from Carson McCullers: “I must go home periodically to renew my sense of horror.”