“The way in which each human infant is transformed into the finished adult, into the complicated individual version of his city and his century[,] is one of the most fascinating studies open to the curious minded,” Mead wrote. “[W]e have been prodigal and blind in our use of these priceless records,” but the curious-minded could change that, by seeking to “read the answers written down in the ways of life of different peoples.” In other words: All over the world, parents are trying to figure out how to parent—and they have been for millennia. Their practices and theories might offer valuable lessons.

Nearly 90 years later, Robert LeVine, an anthropologist and emeritus professor of education and human development at Harvard University, and his wife Sarah, a former research fellow at Harvard, have read the answers provided by parents around the world, and they’ve attempted to make sense of them. They’ve found those answers in the fieldwork they conducted over the past 50 years in Africa, Latin America, and South Asia, and in other studies by academics, journalists, pediatricians, and developmental psychologists. And their new book poses one concise question: Do parents matter?

Their response: Parents don’t matter as much as many parents think they do. For me—a father of a toddler—this discovery was at once deflating and reassuring. The book’s thesis can invite a kind of parental nihilism: I could read Goodnight Moon to him every night, or I could not. Does any of it really matter? But it also invites parents to be more relaxed.