Jean Strouse’s book, “Family Romance,” isn’t a biography of John Singer Sargent, or a definitive history of the Gilded Age or its trappings, Jackson Arn writes. “It contains an astute eye for the era’s swerves and twists.”

 Jean Strouse’s book, “Family Romance,” isn’t a biography of John Singer Sargent, or a definitive history of the Gilded Age or its trappings, Jackson Arn writes. “It contains an astute eye for the era’s swerves and twists.”