Book excerpt: Why do we behave the way we do? Biologist Paul Ehrlich suggests that although people share a common genetic code, these genes "do not shout commands at us...at the very most, they whisper suggestions." He argues that human nature is not so much result of genetic coding; rather, it is heavily influenced by cultural conditioning and environmental factors. With personal anecdotes, a well-written narrative, and clear examples, Human Natures is a major work of synthesis and scholarship as well as a valuable primer on genetics and evolution that makes complex scientific concepts accessible to lay readers.