Wilson and Seaman (1990) conducted a study on incarcerated serial killers, and what they concluded was the most influential factor that contributed to their homicidal activity. Almost all of the serial killers in the study had experienced some sort of environmental problems during their childhood, such as a broken home caused by divorce, or a lack of a parental figure to discipline the child. Nearly half of the serial killers had experienced some type of physical or sexual abuse, and more of them had experienced emotional neglect.