The debate over whether American parents are too permissive began long before anyone had heard of the Tiger Mom — even before we started using the word parent as a verb. Back in 1946, pediatrician Benjamin Spock published a child-rearing book that advocated all kinds of tactics we take for granted today, from on-demand feeding for babies to the idea that fathers should play an active role in parenting. Spock advised readers to relax: “You know more than you think you do.” The book was a hit, though critics slammed the doctor for creating a generation of wimpy parents and spoiled children. But whether you believe that a family culture that brought us Bill Gates and Steve Jobs can’t be all bad, or you blame the doctor for an epidemic of toxic self-esteem à la Charlie Sheen, there’s no denying that the book, which has sold more than 50 million copies, has made its mark on the nation.