Many of the essential human questions-who we are; how much of what we are is due to our personal history, education, and experiences; how we change; how much our essential characteristics can change; and what happens during growth and childhood-are among the questions that underlie developmental psychology. Although everyday folk psychology provides potential answers to these questions-such as “The child is father to the man”; “As the twig is bent, so grows the tree”; “The child is a blank slate”; and “From little acorns grow mighty oaks”—the answers are often contradictory, some implying that our essential characteristics are independent of experience, and others that we are molded by our own specic life trajectories.