Serial Killers: Nature or Nurture?
Serial killers. What leads some human beings to commit unspeakable acts not just once, but over and over again? Does the potential lie in wait in all of us? Or are serial killers victims of poor genetics, condemned in the womb, and doomed to a life of crime? Today, we're exploring a chilling question: Why do some people become serial killers and what do they have in common? As it turns out, it's a complex mix of nature and nurture, biology, and circumstance.
Childhood
Childhood is often where these stories start. Many serial killers report histories of severe childhood abuse. A 2005 study of 50 convicted killers found that 36% experienced physical abuse and 26% endured sexual abuse. Jeffrey Dahmer, who killed 17 people, grew up in a violent home environment, and Richard Ramirez, the "Night Stalker," was haunted by brutal beatings from his father.
Yearbook photo of Jeffrey Dahmer as a senior in high school, 1978. Photo courtesy of Revere Senior High School, Richfield, Ohio. Public domain.
These early traumas may contribute to emotional desensitization, a quality shared by many serial killers. Children exposed to repeated trauma often shut down emotionally, suppressing empathy and sometimes struggling to recognize the impact of their actions on others. However, only a small fraction of abused children grow up to become killers.
According to Dr. Louis Schlesinger, a psychologist at John Jay College of Criminal Justice, it usually takes abuse, hormones, chemical makeup, a head injury, trauma, and/or poor parenting.
Another theory, the Macdonald Triad, suggests that certain childhood behaviors might hint at future violence: cruelty to animals, fire-setting, and bedwetting. The last one may seem out of place, but chronic bedwetting in childhood can sometimes signal psychological distress. Although the theory isn't foolproof, the connection between cruelty to animals and future violence is especially well-documented. Jeffrey Dahmer, for example, mutilated animals before moving on to human victims, as did the Boston Strangler, Albert DeSalvo.
Psychopathy
Defined by a lack of empathy, impulsivity, and a certain superficial charm, psychopathy is a personality trait marked by manipulative and often antisocial behaviors. A staggering 87% of serial killers meet the criteria for psychopathy, and most also display a strong propensity for sadism.
Yet, not all psychopaths are serial killers. Many find success in high-stakes fields like business or politics, where their emotional detachment can be an advantage. The critical difference between these individuals and violent offenders often lies in another trait: sadism. Research reveals that almost 90% of sexual serial killers not only have psychopathy but also exhibit sadistic tendencies, finding gratification in inflicting harm. For them, the act of killing is more than a crime; it's an emotionally charged ritual.
The Warrior Gene
Let's add another ingredient to the mix: the so-called "warrior gene," also known as MAOA. This gene has been linked to aggression and risk-taking behaviors, often associated with violence. Neuroscientist Jim Fallon, who has studied this gene, notes that it doesn't create a killer on its own. Instead, it's like a match, and a traumatic upbringing is the spark. When combined with childhood abuse, the MAOA gene may amplify violent tendencies in individuals already prone to aggression.
However, having the warrior gene doesn't doom someone to a life of crime. Many people carry it and live perfectly peaceful lives. It's only when this genetic trait combines with specific environmental stressors — particularly severe childhood trauma — that it may tip the scales toward violent behavior. It's another piece in the complex puzzle, showing how a person's biology and environment work together.
Society
Finally, let's turn the mirror back on ourselves. Does society play a role in creating serial killers? The fascination with their stories, the media attention, and even the "fans" some killers attract raise tough questions. Serial killers have existed throughout history — think of Jack the Ripper. But it was the 20th century that transformed them from "monsters" into dark icons. The media's portrayal and public fascination create a cycle that can fuel these individuals' desire for notoriety.
Are we, in some way, complicit? This glorification and morbid curiosity surrounding serial killers may amplify the crime's impact, giving killers the attention they crave. For some, that notoriety becomes part of the appeal. Society's fascination with serial killers could inadvertently reinforce the psychological needs that drive them.
Conclusion
As we step away, the question lingers: are killers born, or are they made? Most psychologists agree it's a haunting blend of both. Genes may predispose, early experiences may scar, and society may amplify. But even with all of these factors, the leap from enduring suffering to inflicting suffering is one few will ever take.
References: Speaking of Psychology: Understanding the mind of a serial killer, with Louis Schlesinger, PhD | Serial Killers | Are serial killers born or made?
