There is nothing "deterministic" about biological--or even genetic--explanations for violence, since biology is always affected by experience and context, including prenatal experience. There is no evidence for biological differences between races on measures of aggressiveness, and biologists studying aggression are examining structures and processes shared by all humans. We need to know more about how brain systems involved with aggression develop at critical periods in infancy and childhood, as well as more about the phenomenon of permanent neurological changes after long-term victimization, which has implications for victims of child abuse as well as those suffering post-traumatic stress disorder. Neuroscientists are now engaged in relating the many brain areas and functions involved in the range of complex behaviors we call "aggression," and will someday be able to suggest therapies for particular problems which contribute to violent behavior in some people.