Moore was born Julie Anne Smith on December 3, 1960, at the Fort Bragg army installation in North Carolina. Her father, Peter Moore Smith, a paratrooper in the United States Army during the Vietnam War, attained the rank of colonel and became a military judge. Her mother, Anne, was a Scottish psychologist and social worker from Greenock, Renfrewshire, who had migrated with her family to the United States in 1951. Moore has a younger sister, Valerie Smith, and a younger brother, the novelist Peter Moore Smith.