One reason that true crime fascinates so many of us is that we’re curious about what motivates the perpetrators. What drives someone to kill – especially if they do it more than once? And do serial killers feel guilty and ever regret their crimes?
For decades, psychologists have been attempting to unravel the dark and complex minds of these rare individuals – with findings supporting prevention efforts and contributing to society’s understanding of criminal psychology.
While research in this area is still ongoing and it’s impossible to place people in clearly defined boxes; some traits and experiences are commonly linked with serial killers.
Below, we’ll consider whether serial killers are born or made and whether it’s really possible to predict whether someone is predestined to kill.
Trigger warning – This article contains themes of extreme violence and sexual abuse. Reader discretion is advised and our thoughts are with anyone who may have been affected by any of the tragic events mentioned here.
What factors may contribute to the creation of a serial killer?
Though various factors could contribute to an individual’s reasons for committing multiple murders, some seem to crop up time and again. These include…
Childhood abuse
Though not all serial killers are abused as children and not all abused children become serial killers, research does show that childhood abuse is more common in ‘lust killers’ (those who kill for sexual gratification).
For example, one landmark US study of the history of 50 convicted serial killers found that 36% had suffered physical abuse and 26% had suffered sexual abuse.
Plus, in Robert Ressler’s book, Whoever Fights Monsters, 40% of the serial killers interviewed reported being physically beaten and abused in their childhoods, and 70% reported that they had “witnessed or been part of sexually stressful events” as children.
To look at a few examples of notorious serial killers who have been sexually abused as children…
- Richard Ramirez from El Paso, Texas killed 13 people in San Francisco and Los Angeles. Growing up, he endured brutal beatings from his father.
- Jeffrey Dahmer killed 17 boys and men between 1978 and 1991. His crimes involved rape, necrophilia, dismemberment, and cannibalism. In 1991, Dahmer’s father reported that his son was molested by a neighbour at the age of 8. His parents also had a toxic relationship and the police were often called to their family home to break up fights.
- Fred and Rose West raped and killed 12 women and girls between 1967 and 1987. Rose’s father was a paranoid schizophrenic who regularly sexually abused her. Her mother also received shock therapy in the late stages of pregnancy, which, some psychologists feel, could have affected Rose’s development. Fred also claimed that his parents abused him as a child – though his brother has since disputed this, saying there was no abuse in their home growing up.
The experiences we have in early childhood can have a profound effect on shaping our personality and life choices. It’s a common belief among psychologists that individuals who experience early childhood abuse may learn to suppress their emotions and, therefore, never learn the appropriate response to trauma.
One study which looked at abuse/neglect in childhood suggested that “a child might become ‘desensitised’ to future painful or anxiety-provoking experiences” and that this desensitisation might make “him or her less emotionally and physiologically responsive to the needs of others, to be callous and lack empathy, and to lack remorse or guilt.”
Abuse may also affect a child’s sense of morality, especially when they’re abused by people whom they love and trust, like a parent. For some children, abuse may even become normal – and they may not understand it’s wrong – while others may become bitter as a result of their experiences and look to seek revenge by harming others.
Psychopathy
Psychopathy is a personality disorder commonly linked to serial killers. Individuals with psychopathy exhibit a specific pattern of behaviour that sets them apart from the general population.
Some of the key features associated with psychopathy include…
- Lack of empathy. Psychopaths have difficulty understanding or feeling the emotions of others. They often lack compassion and fail to recognise the impact of their actions on others.
- Superficial charm. Psychopaths can be charming and charismatic, but this charm is often used to manipulate others for personal gain.
- Impulsivity. They tend to act impulsively without considering the consequences, which may lead to risky behaviours and criminal acts.
- Deceitfulness. Psychopaths are skilled at lying and manipulating, and may create elaborate stories to deceive others.
- Shallow emotions. While they can experience emotions, their emotional range is limited. They may not feel deep sadness, guilt, or remorse.
- Irresponsibility. Psychopaths often fail to take responsibility for their actions, blaming others or external circumstances instead.
- Lack of remorse. Even when they harm others, psychopaths rarely feel remorse or regret.
- Antisocial behaviour. Psychopathy is closely linked to antisocial behaviour, including criminal acts, aggression, and disregard for societal norms.
As you might expect, there’s a strong link between early childhood abuse and developing mental health disorders, such as psychopathy, later in life. Though, of course, not all children who are abused develop psychopathy, and not all psychopaths have been abused as children or go on to become serial killers.
However, research by Columbia University professor Michael H. Stone, who looked at the biographies of 89 male sexual serial killers, reported that 87% met the criteria for psychopathy, according to the Hare Psychology Checklist. 88% also had a sadistic personality disorder, meaning they got sexual gratification from hurting others.
In another study, which looked at 36 German serial killers, 86% had at least one personality disorder – with 36% meeting the criteria for psychopathy.
Some well-known examples of serial killers who psychologists believe to be psychopaths include Ted Bundy and Charles Manson.
With all this considered, it’s essential to note that not all psychopaths are violent or criminals. Some psychopaths lead successful lives in various fields, such as business or politics. The diagnosis of psychopathy is typically made using specialised assessment tools, and it remains a complex and controversial area of study.
The ‘warrior’ gene
There have been many questions raised about whether people are born serial killers or whether environmental factors are the cause. But most psychologists agree that it’s often a combination of both.
When it comes to genetics, some individuals have a variant of an enzyme called monoamine oxidase A (MAOA) – nicknamed ‘The Warrior Gene’ due to its associations with aggressive and risk-taking behaviours.
MAOA plays a key role in breaking down the neurotransmitters responsible for positive emotions – such as noradrenaline, serotonin, and dopamine. And, having levels of MAOA that are too high or low can have negative effects on our mood and behaviour.
While you would think that having low levels of MAOA would have a positive effect because of the increase in happy hormones; research has revealed that people with low-activity MAOA are often more sensitive to negative stimuli, leading to heightened aggression.
In his TED Talk, Exploring the Mind of A Killer, Neuroscientist, Jim Fallon, explains that the MAOA gene is more common in men, and suggests this may be why more men are serial killers. However, this gene alone is not normally enough to drive someone to kill – and, in fact, Fallon himself, is a carrier of the gene.
Fallon spent 35 years studying the minds of serial killers. After analysing 70 brains (without knowing who was a serial killer and who was a regular person), he suggested that three high-risk factors could exist in someone without leading to murder: brain damage, having the MAOA gene, and overexposure to serotonin in the womb.
But, Fallon believes that the fourth factor – witnessing extreme violence at a young age, before puberty – could be the trigger needed to push someone to commit murder.
The MacDonald triad
In addition to the factors above, other psychological research suggests that there are a group of behaviours in childhood that may be predictive of, or linked to violent tendencies. These behaviours are animal cruelty, bedwetting, and fire setting.
The theory came about after J.M. Macdonald published a controversial review in 1963, which examined earlier studies and suggested a link between these behaviours and violent tendencies in adulthood.
Let’s take a look at each of the behaviours and its role in the triad in more detail…
- Cruelty to animals – Children who harm animals, especially pets, may feel disempowered and be looking to feel a sense of control over their environment. Macdonald suggested that this may be particularly true of children who’ve experienced prolonged abuse by adults.
- Fire setting – Similar to animal cruelty, children may start fires as a way to vent feelings of anger, and attempt to gain a sense of control over their environment.
- Bedwetting (after five years old and for several months) – Of the three triads, bedwetting is often seen as the most surprising, as not many people would automatically connect it with murder. However, MacDonald suggested that bedwetting may add to the humiliation that a child feels at the hands of their abuser, and perpetuate the other triad behaviours. Plus, the more a child wets the bed, the more anxious they may feel, which then creates a cycle – as anxiety and bedwetting go hand in hand.
Though Macdonald didn’t find any definitive links between the triad and adult violence, his work inspired other psychologists, who’ve continued to test these findings. For example, in 1966, psychologists Daniel Hellman and Nathan Blackman looked at the histories of 88 people convicted of violent acts of murder and discovered that while 31 of them had the full triad, 57 only fulfilled the triad in part.
So where are we with the theory today? At present, psychologists tend to agree that there may be some element of truth in the MacDonald triad. But, due to insufficient evidence, it’s far from reliable in predicting whether somebody is likely to commit serial violence or murder later in life.
That said, animal cruelty is one aspect of the triad that is commonly seen in the childhoods of serial killers. For example, research into US school shooters found that 45% of them had harmed animals in the past; while studies of aggressive inmates found that a quarter of them had animal abuse tendencies as children.
Jeffrey Dahmer and the Boston strangler, Albert Desalvo, are examples of serial killers who are believed to have targeted animals as children, before moving on to people. Jeffrey Dahmer practised cutting up dogs and cats before dismembering people, while Albert Desalvo locked cats and dogs in crates and shot them with a bow and arrow until they died. He then went on to murder 13 women in the 1960s.
Final thoughts…
Despite decades of research and TV documentaries like Channel 4’s What Makes a Murderer attempting to unpick the complex minds of serial killers, the reality is that psychologists are still unsure what drives some people to kill. And there are a myriad of different factors at play.
While, certain traits and experiences have historically been linked to serial killers – including psychopathy, genetics, child abuse, and the Macdonald triad of behaviours – these cannot accurately predict whether someone is likely to grow up to commit serial murders.
For now, psychologists tend to agree that serial killers are neither purely born nor entirely made and that the truth lies somewhere in between. Their behaviours result from a mix of genetic, environmental, and psychological factors – and further research and understanding of these factors can be useful in the prevention, intervention, and rehabilitation of serial killers.
For further reading, check out our article on 7 of the UK’s most prolific serial killers.
Do you find this article interesting? Are there any other true crime topics you’d like us to cover? We’d be interested to hear from you in the comments below.