As the study of human genetics has unveiled genetic contributions to differences in intelligence, personality, and psychopathology, criminologists have begun to examine the hypothesis that people also vary in the susceptibility to crime for genetic, as well as sociological, reasons. Evidence for genetic influences has arisen from studies of twins, adopted children, and chromosomal abnormalities. It appears that family environment, as opposed to family genes, has a minimal impact on an individual's personality. Family members who have common characteristics have common genes; likewise, criminality in the natural parents of adopted children is more predictive of crime than such behavior in the adoptive parents. A particular chromosomal abnormality, in which some men inherit two X chromosomes from their fathers, is ten to twenty times more prevalent among institutionalized offenders than non-offenders. Although there is a link between criminality and another genetic trait, low intelligence, the link is probabilistic not deterministic. There are fewer female than male offenders, however they are more deviant, both intellectually and personally. Maternal substance abuse, birth trauma, head injury, and disease all contribute to criminality. Individual differences matter in that changes in the proportion of teenagers and young adults change the aggregate crime rate. The social contribution to the rising crime rate is that as the United States becomes more secular and less moralistic, young people are not taught moral behavior. Weak moral education and procedural delays in the criminal justice system undermine criminal sanctions. An effective crime prevention perspective would include a diversification of curricula and instruction that would loosen the ties between success and standard academic intelligence, support for criminal punishment along with sympathy for the victims of crime, and benevolent use of the ability to predict criminal behavior in individuals. 39 references.