The early biopsychosocial development of boys and the origins of violence in males.

We apply a biopsychosocial approach to introduce early-in-life experiences that explain a significant part of the male preponderance in the perpetration of violence. Early caregiver abuse and neglect, father absence, and exposure to family and neighborhood violence exacerbate boys' greater risk for aggressive behavior and increase the probability of carrying out violent acts later in life. We examine the development of the psychological self and explore conditions that encourage physical aggression, focusing on the impact on the infant and toddler's emergent mental representation of self, others, and self-other relationships. Boys' slower developmental timetable in the first years of life may enhance their vulnerability for disorganization in emergent neurobiological networks mediating organization of socioemotional relationships. Emergent attachment and activation relationship systems may differentially affect risk and resilience in boys and girls, particularly in single-parent families. Evidence has suggested that the dramatic increase in single-parent families is especially linked to corresponding increases in behavioral undercontrol, antisocial behavior, and the emergence of violence in boys.