John was born and reared in Chicago, received an undergraduate degree from Augustana College in Illinois and his graduate degrees from Washington State University. He completed a post-doctoral fellowship in Medical Psychology at the University of Oregon Medical School. John has been on the faculty of the Department of Psychology at The University of Iowa since 1969. The central focus of his research has been the causes and consequences of child maltreatment and the development of aggression and antisocial behavior. His teaching has focused on clinical research methodology and clinical practica pertaining to forensic evaluations in child maltreatment and child custody determinations.