HERBERT RENZ-POLSTER, MD, is a pediatrician and researcher specializing in infant development. His bestselling books have inspired countless families in Germany and established him as a leading voice in the parenting debate. He also contributes to the discussion through social media (@kinderverstehen. de) and his website, kinder-verstehen. de. He is the father of four children and grandfather of five grandchildren. He lives with his wife near Lake Constance. Contact: Herbert. Renz-Polster@kinder-verstehen. de