Biological Influences on Criminal Behavior, Second Edition is fully updated to include recent research, studies, and publications examining the integration of the biological view with mainstream social, psychological, and environmental views in influences in criminality and criminal behavior. The first edition of the book was written with the belief, grounded in research, that something vital can be discovered when we assess all the factors related to the causes of crime, including biology. Since the first edition published, it has become broadly accepted that biology is certainly a factor in criminal behavior, albeit a singular piece to the puzzle. Increased collaborations between scientists and criminologists has led to a much stronger understanding of the intricacies of biology’s role in behavior. As well, more criminologists have biological backgrounds. As the science involved became more complex, so too did this text. This second edition considers the more recent and integrated research that is being conducted today to show the interaction between the environment and a person’s biology that lead to our behavior. It has even been shown that the environment acts on, and actually changes the functions, of some genes. The book begins with basic scientific principles and advances to introduce the reader to the more in-depth discussions of various biological influencers. Biological Influences on Criminal Behavior, Second Edition is written primarily for social science and law students who wish to understand this exciting area. The book offers a greater understanding of this rapidly growing field so that its lessons can help to inform policy, treatments, rehabilitation and the law.