What Creates Serial Killers and Psychopaths: Genetics or Environment?

Published on by Raven


     It has been thought for a long time that people become violent because they are “crazy”. Other people have thought that people become violent because of a horrendous childhood that included abuse, neglect, and rejection. Which is it? Researchers have been working for many years to figure out what causes a person to become a serial killer or a psychopath, but there is still no concrete answer. Serial killers are always psychopathic, but not all psychopaths are serial killers. However, all psychopaths have many common traits. These traits involve family history, or genetics, as well as environment and experience. Most of the research can show that there is no one cause for violent behavior. Although serial killers and other psychopaths may have brain abnormalities or dysfunctions, personal experience and environment also play a large role in the molding of a monster.

     Psychopaths and serial killers are subject to constant research. Not only are people fascinated by their callousness, but people also want to learn what makes them what they are. It is always said that knowledge is power. If we could gain enough knowledge through research, then it may be possible to reprogram these violent people.

     Psychopathic serial killers are, almost without exception, males who are driven by a sexual or aggressive drive to exert power and control by killing another living, breathing thing (Osterburg and Ward, 2004). John Douglas explained in his book, The Mindhunter, that most serial killers are not psychotic. “Psychotic” implies that a person has a psychosis that has caused him to lose touch with reality, and have episodes like hearing voices or delusional behavior, and serial killers do not have this condition. He says that serial killers are psychopaths who suffer from chronic mental disorders coupled with violent and aggressive social behavior (Douglas, 1996). Does this mean that serial killers are crazy or insane? The answer is no. Serial killers are the most extreme form of psychopaths, but are not crazy or insane in any sense of those words.

     In a paper for the International Association of Forensic Sciences in 1984, FBI Special Agent Robert Ressler and some of his colleagues listed 10 characteristics of a serial killer. Over 90% of serial killers are white males who have IQ’s in the normal to bright range. Even with this intelligence, though, they do poorly in school and often have problems keeping a job. They tend to come from highly unstable or dysfunctional families, usually abandoned by their fathers and raised by controlling mothers. They usually hate their parents. Almost every serial killer is abused as a child, whether it is sexually, emotionally, physically, or psychologically. This abuse may come from a stranger or a family member, but many serial killers try to lie about this history of abuse. Most serial killers have records of early psychiatric problems and often spent time in institutions as children. They have an intense interest in voyeurism, fetishism, and sadomasochistic porn at a very early age, and they also have a very high rate of suicide attempts. Future serial killers share three other traits in their childhoods. More than 60% of serial killers wet their beds past the age of 12. They also have a fascination with fire, which may be an early manifestation of their fondness for mass destruction. In addition, almost every serial killer starts his abuse and sadistic torture on animal victims (Fisher and Fisher, 2003). 

     Now that the profile of a serial killer is known, one has to examine the characteristics of a psychopath. After all, serial killers are extreme psychopaths, so they will also fit this profile. Charles Montaldo, who wrote the article “Characteristics of the Psychopathic Personality,” says that a psychopath is incapable of feeling guilt, remorse, or empathy for his actions. He is generally cunning and manipulative. He knows the difference between right and wrong, but dismisses it as not applying to him. A psychopath is also incapable of feeling normal emotions like love, and often shows extreme egocentric and narcissistic behavior.

     In addition to Montaldo’s characteristics, it has been shown that a psychopathic individual also has intelligence and charm. He has no delusional or irrational thinking.  He is also untruthful, insincere, and unreliable. He displays anti-social behavior and poor judgment, and fails to learn from experience. He comes from general poverty, his sex life is impersonal and poorly integrated, and he fails to follow any real life plan. He is also unable to control outbursts of anger or hostility, which often causes his inability to hold down a job or keep associations with family and friends. The consequences of his actions, in his mind, give him justification for even more aggressive behavior. Of course, the main downfall of the psychopath is that he always thinks that he is smarter than everyone else is. He believes that he can outwit all other people, and that he can commit any crime without ever being charged or convicted. He believes that even if he is caught that he can “talk” himself out of trouble. Is it any wonder why psychopaths often become serial killers?

     Once one puts these profiles of serial killers and psychopaths together, the actual person begins to emerge. It is no longer just a sheet of facts, but a profile of a monster. So how can one tell if a person is a potential serial killer? Evan Sycamnias says that several traits can indicate a potential serial killer, but these traits are very general. A person who is already a psychopath and is on the verge of becoming a serial killer will usually become socially withdrawn, although he may display attention-seeking behavior like hypochondria. He may also suffer from severe depression and have a general feeling of emptiness about his future. He will fail at every attempt to succeed, but be unable to take criticism. He will have delusions of grandeur, or a feeling that he is superior to everyone in some way. He will usually suffer from mood disorders and have an abnormal dependence on his mother, or other abnormal relationships with his parents. He will feel like he is being mistreated, but be unable to assert himself. In most cases, his parents will taunt him as to his ability to be sufficient (Sycamnias, Evan). Once one looks at all these traits of serial killers, psychopaths, and potential serial killers, it becomes apparent that environment and experience make a huge impact on what these people become. It also seems that some of these lists contradict themselves. How can a person who always fails and feels so empty and hopeless possibly have delusions of grandeur? It does seem that a person who has the characteristics of a potential serial killer would be more likely to commit suicide than murder, but the other aspects must be considered as well. A psychopathic, potential serial killer who cannot form relationships with others may have to take other people “hostage” in order to have company. If he feels that he is mistreated and he cannot assert himself, then he may be searching for a situation that he can control. He wants to be in charge. He uses murder and torture as a means of paying society back for dismissing him. This allows him to see himself as dominant, controlling, and powerful. Many serial killers even perceive themselves as God because they control whether a person lives or dies. Since many of these serial killers suffer from mood disorders like bipolar disorder, there is often a personality clash inside of them. They may go through a point where they know that they cannot control themselves any longer and wish to be caught so that they can stop. However, the extremes of the mood disorder cause them to regain control of themselves in order to continue their “work” and avoid discovery (Apsche, 1993). So what causes this psychopathy? Many of the characteristics point to environment and experience, so where is the evidence of brain abnormality or dysfunction, or genetic precursors?

     Robert Hare specializes in the study of psychopaths. He characterizes them as “intraspecies predators who use charm, manipulation, intimidation, and violence to control others and satisfy their own selfish needs,” (as quoted in Crime Times, 1997). Hare also says that a psychopath’s egocentricity is what makes him so particularly dangerous. “Lacking in conscience and in feeling for others, psychopaths cold-bloodedly take what they want and do as they please, violating social norms and expectations without the slightest sense of guilt or regret,” (as quoted in Crime Times, 1997). 

 In fact, psychopaths make up at least a quarter of the prison population, and an FBI study found that almost half of all law officers killed in the line of duty were killed by psychopathic individuals (Crime Times, 1997).This psychopathic behavior has traditionally been blamed on environmental or experiential factors, but more evidence is starting to indicate that there are fundamental differences in the psychopathic brain. Could this mean that bad parenting, environment, and even experience could all be irrelevant factors?

     “Psychopathy is associated with abnormalities in attention and orienting” (Kiehl, Bates, Laurens, Hare, and Liddle, 2006). The authors of this article conducted a study of 80 incarcerated men that were classified as either psychopathic or nonpsychopathic. When these men processed the targets, the psychopaths had a larger amount of frontocentral negativities than nonpsychopaths did. Psychopaths also showed an enlarged N2 and reduced P3 during target detection. Similar results have been found in patients with temporal lobe damage or amygdala. These results show that psychopathy may be linked to dysfunction of the paralimbic system-a system that includes part of the temporal and frontal lobes (Kiehl, Bates, Laurens, Hare, and Liddle, 2006).

     In 1995, Christopher Patrick reported that psychopaths have smaller heart rate changes and skin conductance changes in response to fear-provoking sentences than do the control subjects. This result indicates that the processes that create normal emotion in a regular person are defective in a psychopath (Crime Times, 1995). Dominique LaPierre’s research also suggests that the prefrontal cortex does not function normally in psychopathic subjects (Crime Times, 1995). Patrick has done further research on these individuals and concluded, “the absence of normal startle potentiation in psychopaths during exposure to aversive pictures or warning cues signifies a deficit in capacity for defensive response mobilization, which is the essence of fear” (as quoted in Crime Times, 1997).

     Studies by Rodney Day and Stephen Wong show evidence that psychopaths do not react normally to stimuli because they rely more on the left hemisphere of their brains, which uses a more verbal-analytic strategy than the right side does. The conclusion of their study is that the abnormal processing of emotional stimuli by psychopaths may be limited to language (Crime Times, 1997).

     Psychological deficits in serotonin levels have been associated with psychopathology involving excessively aggressive behavior. Serotonin also offsets the violent and aggressive effects of testosterone. Violent personality disorders often have both low serotonin levels and high testosterone levels (White, 2001). It seems to make sense that testosterone could be related to violent behavior and psychopathy, since most severe cases of psychopathology occur in men.

     Physical brain trauma has also been associated with violent tendencies. “A 1986 study examined the neurological histories of fifteen death row inmates, and found that every member of the experimental population had experienced severe head injury prior to incarceration. Five had significant neurological impairment, seven were less intensely afflicted, six were diagnosed with schizophreniform psychoses, and two were manic-depressive. Because the inmates were selected without prior awareness of their mental conditions, the diversity and prevalence of these pathologies within the experimental group can be used to infer the high incidence of abnormal brain function within the population of violent offenders” (as quoted by White, 2001).

     Certain brain structures control certain things. For example, the hypothalamus contains the brain’s center for sexual response and aggression, so hypothalamic damage can produce violent and destructive behavior. This can be centered on an abnormal psychological connection between sexual instinct and violence (White, 2001). These problems can result in an individual’s inability to separate sexual excitement and violence.

     The limbic system of the brain contains the structures that control memory, emotion, and parental and social instincts. If this brain system is damaged, an individual may no longer have the ability to react appropriately to social expectations. If the damage is extreme, the individual may even display repetitive violence against others. If there is damage to the temporal lobe, an individual may have amnesia, epilepsy, and increased frequency and reduced threshold of violent responses. This temporal lobe damage has been cited as a cause in many murder cases (White, 2001).

    Some research shows that there may be a genetic factor that results in a behavioral predisposition to violence (White, 2001). However, no single gene that causes aggression or violence has been isolated. Several studies have associated psychological disorders associated with aggression back through ancestry. There are more various psychopathologies in the families of young patients with borderline personality disorders than in control group families. It was also observed that a group of children with criminal and/or socially maladapted parents had abnormally elevated levels of social delinquency and aggression. The researchers that conducted these studies conclude that both genetics and environment play a role in violent behavior, “bad seeds [i.e. products of violence-predetermining genetics] blossom in bad [i.e. negligent, abusive, or violence-glamorizing] environments” (as quoted by White, 2001).

     After reviewing all of the research at hand, one can determine that there are certain unavoidable factors that can cause a person to be a serial killer or psychopath. Brain damage, disorders, brain chemicals, hormones, and family history certainly seem to create problems in a person. However, any intelligent person has to question why the characteristics of serial killers and psychopaths always involve their childhood horrors of abuse and neglect. If a serial killer or psychopath is born, then why do they share these experiences? If a person is born this way, then why do they all come from similar backgrounds instead of crossing all social and economical boundaries?

     According to Dr. Dorothy Lewis, a professor of psychiatry at NYU Medical School writes about circumstances that promote extreme violence. “They are the combination of a history of extraordinary, early ongoing abuse, some kind of brain dysfunction and psychotic systems, particularly paranoia. The more serious the neurological and psychotic symptomology, if the individual has been abused, the more violent the individual seems to be. Also, the assumption that mental illness necessarily results in violent, antisocial behavior is a false one” (as quoted by White, 2001).

     Debra Niehof, a neuroscientist, agrees with the notion that psychopathic behavior cannot be linked to one source. Serial killers and psychopaths are very complicated individuals. Both genes and environment modify each other so that a response of violence is unique to an individual. Generally speaking, the same stimulus will not cause the same response in every person. “The biggest lesson we have learned from brain research is that violence is the result of a developmental process, a lifelong interaction between the brain and the environment” (as quoted by Ramsland, 2006).The chemistry of aggression is associated with the chemistry of attitude. A person’s ability to evaluate a situation can be impaired. “If a person has come to believe that the world is against them, and they are overreacting to every little provocation, these violent reactions get beyond their ability to control, because they are in survival mode” (as quoted by Ramsland, 2006). Niehof says, “It is important to understand that violence has no one single cause. It can come from any part of the psychological structure. Everything that we encounter or experience in our lives has the potential to affect us, and there is no single factor to target for blame. Violence is the result of a complex feedback loop, but it’s one that can be broken. Biology is not destiny.” Niehof has concluded that the brain is flexible and that it can actually relearn patterns by way of new experiences. She claims that we can reduce violence whether it comes from genetics or environment. All we have to do to change it is to create a safe and caring environment (Ramsland, 2006).

     Although one can clearly see that genetics, brain chemistry, damage, or dysfunction, or history of mental problems can cause a person to become a serial killer or psychopath, but that is not all it takes. Children who grow up in a violent home do not develop the social skills that they need to function as normal adults. It has been proven that a strong factor in the development of antisocial behavior is a child’s lack of connection with others. Therefore, parents who make no effort to bond with their babies in the first three to nine months may actually be causing the antisocial personality. It has also been proven that the lack of safety in children causes harm to cognitive function. Living in a violent household can also cause children to live in fear, which causes them to repress feelings and hinders their ability to empathize. They also have a difficult time concentrating, and often feel helpless. On top of all these problems, a child who lives in constant stress will display symptoms of Post Traumatic Stress Disorder.   

     There are also certain factors that affect the risk of future violence in kids. These factors are past violent behavior, substance abuse, aggressive peers, family aggression, social stress, character or mental disorders, access to weapons, focused anger, and a low degree of resilience. It is known that self-worth, resilience, hope, intelligence, and empathy are essential to building character for effective impulse control, anger management, and conflict resolution. Without these skills, children cannot establish proper relationships with the community. “While a born psychopath may have neurological disorders that defy every treatment, it still seems to be the case that many criminals with certain psychopathic traits may be turned toward something pro-social with the right nurturing” (Ramsland, 2006).

     With all the research on serial killers and psychopaths, we should know all the answers without question. However, we need to study the brains and lives of every serial killer and psychopath from birth until death to be sure why they are what they are. One has to believe that it is a mixture of both, since no reasonable person could possibly rule out the importance of any one factor. The most important research is the research that shows that these people can be “redesigned” by a nurturing and caring environment; animal breeders can prove this theory. A person who has a fierce rottweiller that comes from a long line of fighting dogs bred for meanness and ferociousness can turn this dog into a sweet, loveable, lap dog with the right care and nurturing. However, there are extreme cases where the dogs are so mean that they just have to be euthanized. For the most part, however, the right environment can change the animal’s behavior completely. It would seem that the same reality would apply to people, and research shows that it does. In my opinion, it is not realistic to think that all of the psychopaths and serial killers in the world can be saved, but if we can catch the signs early in childhood, we may have a chance. Even though their brains may have abnormalities, we can certainly try to change their environments to redirect their development.



Apsche, J. (1993). Probing the Mind of a Serial Killer. International Information Associates.

Douglas, J. (1993). Mindhunter. Mandarine Publishing.

Fisher, K., and Fisher, R. (2003). Common Characteristics of a Serial  Killer. Retrieved August 8, 2006, from the World Wide Web;  http://www.carpenoctem.tv.

Kiehl, K. A., Bates, Alan T., Laurens, Kristin R., Hare, Robert D.,  Liddle, Peter F. (2006). Brain Potentials Implicate Temporal Lobe Abnormalities in Criminal Psychopaths. Journal of Abnormal  Psychology, 115(3). Retrieved January 25, 2007, from the Proquest Criminal Justice database.

Montaldo, C. Characteristics of a Psychopathic Personality. Retrieved January 10, 2007, from the World Wide Web: http://www.crime.about.com.

Osterburg, J.W., and Ward, R.H. (2004). Criminal Investigation: A Method for Reconstructing the Past, Fourth Edition. Matthew Bender and Co., Inc.

 Psychopaths: Findings Point to Brain Differences. (1997). Crime Times, 3(2).  Retrieved August 20, 2006, from the World Wide Web:

Ramsland, K. (2006). The Unthinkable: Children Who Kill.  Retrieved from the World Wide Web:  http://www.crimelibrary.com.

Sycamnias, E. Evaluating a Psychological Profile of a Serial Killer. Retrieved September 12, 2006, from theWorld Wide Web:http://www.crime.about.com.

White, S. (2001). Making a Monster: The Biological, Social, and Artistic Construction of a Serial Killer. From Psychosis to Sondheim. Retrieved from the World Wide Web: http://www.serendip.brynmawr.edu//bb/neuro/neuro01/web3/white.html.



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