For new parents, there’s no shortage of how-to manuals that tackle everything from sleep training to tantrums. But life hacks aside, how exactly does one take a tiny baby and turn them into an emotionally healthy adult?

Your greatest chance for success, argues psychotherapist Philippa Perry, is to understand yourself first. In her bestselling guide to parenthood, The Book You Wish Your Parents Had Read (and Your Children Will Be Glad That You Did), Perry urges parents to understand their “parenting legacy”—that singular narrative of the childhood experiences that have shaped each one of us into the adult we are today. Perry believes that a thorough understanding of one’s own history equips parents to identify—and then avoid—the unhelpful habits that were taught to them as...