[Lilly Pulitzer] Rousseau’s story has been oft-told over the years: Born the middle of three daughters into a socially prominent family in Roslyn, New York, Lilly McKim attended all the right schools (Chapin, Miss Porter’s) with all the right people (Jacqueline Bouvier was a schoolmate at Miss Porter’s) before eloping in 1952, at age 21, with newspaper scion Peter Pulitzer. The pair moved to Palm Beach, where Pulitzer operated a successful citrus grove business, and his bride quickly had three children: Peter Jr., Liza and Minnie. The couple threw fabulous parties, famously tossing water on the tiled kitchen floor of their great big house overlooking Lake Worth so that everyone could do the twist after dinner. Lilly herself became known for “not giving a whit,” according to her longtime friend Susannah Cutts, accruing a menagerie of dogs, cats, monkeys and even a calf (“those awful animals,” Rousseau says now). But…