The authors use evolutionary psychology—in their words, "a Darwinian selectionist habit of thought"—as the main ingredient in a cocktail of information from biology, psychology, sociology, and criminology to create a blended view of what causes juvenile delinquency. That main ingredient is the focus of the first two chapters, which provide a primer on evolutionary biology and behavioral genetics. These chapters are well written but heavy going, and some readers might fear that this genetic perspective on aggression can only end badly—changing the gene pool takes a long time. But perseverance is recommended and rewarded. This foundation for the cocktail, while stiff in undiluted form, offers the interesting texture for later chapters as other ingredients are added.