Nature vs. Nurture: The making of a child serial killer

In 2007, 8-year-old Amarjeet Sada would murder a 6-month-old baby and bury her body. Born in 1998 in a small village in northern India, Amarjeet came from a poverty-stricken family. Though information on his childhood is scarce, it is known that he suffered from some sort of mental illness or personality disorder. His first victim would be his cousin, some reports say she was six years old while others say she was nine months old. Regardless, he strangled her to death then later told his parents. They decided not to tell the police and keep it a family matter. The lack of consequence inspired him to murder again; this time, his 8-month-old sister was the victim. One night when his parents were asleep he strangled his sister and put her back in her crib. Upon discovery, his parents immediately knew he had been the one to kill her. When asked about it he willingly confessed, they once again decided to keep it in the family.

Once again this lack of care and punishment for what he had done allowed him to commit a third time. This time though it wasn’t a family member. A woman had kept her 6-month-old baby in the village school to nap, later on Amarjeet would pick up the baby and take her out, making her his third and final victim. Later on the mother of the child would come looking for her baby leading the village to call the police and question Amarjeet. This is where he would confess to his crimes, dubbing him the title of the world’s youngest serial killer.

This is an unfortunate case amongst many that shows us that even children can kill, whether it is out of cold blood or something else is what we are unsure of. What could possibly lead a child to kill, not once but multiple times at that? Throughout this article we will discuss and look into the reasons this might be so and possible telltale signs if there are any.

Serial killer children

The year 2006, in a quiet town in Alberta, Canada, three members of the Richardson family were brutally murdered in their own home by their own daughter and sister alongside her older boyfriend. 12-year-old Jasmine Richardson had first met 23-year-old Jeremy Steinke in a punk rock concert early that year. Jeremy claimed to be a 300-year-old werewolf on a website (VampireFreaks.com) where the couple both frequented. Jasmine grew up in a normal loving family home, she was once a bright, sociable and well-liked child, but as she grew older she started showing more rebellion and became obsessed with controversial musicians and serial killers. After she had met her boyfriend her parents forbade her from seeing him as he was much older. This formed a strain in their relationship and caused Jasmine to then want to get rid of them. With the help of her boyfriend she orchestrated and executed the stabbing of her whole family, including her seven-year-old brother.

Jeremy on the other hand had a rocky upbringing, his mother was an alcoholic and his parents regularly abused him. His family moved around a lot and so he never got to make long lasting friendships. He was diagnosed with ADHD (Attention Deficit Hyperactive Disorder) and was bullied. He also started drinking and experimenting with drugs early on. All this led to him dropping out of high school by the tenth grade.

The year 1965, in the city of Murcia, Spain, a string of child deaths left people frightened and concerned. It would later be discovered that a 12-year-old by the name Piedad Martínez del Àguila was behind all of them. Piedad was the third of ten children from a poor family. At her young age she was left responsible for seven of her younger siblings whilst also taking care of household chores and working in the light industry. Suddenly her siblings started dying under mysterious circumstances, which law enforcement will later find out was poisoning from cyanide (cleaning tablet) and DDT (insecticide).

At first law enforcement were suspicious of the parents but they were quickly cleared and suspicion turned on Piedad, who was responsible for preparing their meals. Piedad later confessed to killing the four victims, saying that the first three were by order of her mother and the last by her own will. When asked why she had done it, she stated that she grew tired of taking care of them and wanted to play with her friends.

Nature vs Nurture

Nature vs nurture is a long going psychological and philosophical debate. It asks about whether an individual is largely influenced by their nature or by their nurture. Nature refers to our genetics and hereditary traits. These are factors that we are born with and have no control over, such as eye color, hair color, skin color, etc. While nurture refers to our environment and how it affects our opinions, choices and how we handle a variety of situations as we grow up.

Many researchers believe that a lot of traits can come from the interaction of nature with nurture. The ability to detect perfect pitch is an example of that. It is believed that this pitch perfect ability runs in a family through genetics, but the ability will not manifest without musical training in early childhood.

Schools of thought

Plato & Descartes: They believe all of our characteristics and behaviours are directly linked to our genetics, so everything that we do is inborn and cannot be changed or influenced by the environment around us.

John Locke & John B. Watson: They believe that once a person is born they are born with a blank mind or slate so everything that they do or become afterwards is a result of environmental conditioning. They believe that everyone can become anything with enough training and guidance regardless of the genes they have been dealt from birth.

There are others with extreme views called nativists and empiricists. Where nativists believe mostly everything is a result of inherited genes and empiricists believe mostly everything is a result of environmental conditioning.

Areas of debate

Academics: This is a very common arguing point. Many people debate on whether a person gaining academic success is due to the genetics they were born with, or that their hard work and dedication is a result of the environment that allows and encourages them to be and do so.

Violence: A person that abuses others, is it as a result of their genetics or through learning and observation of their environment as they grew up?

Child development: Nativists believe that every child is born with the capacity to learn and produce language, while empiricists believe that children learn by observing the behaviour of others, as shown in Albert Bandura’s bobo doll experiment. He showed that children could learn to be aggressive by simply observing another person’s aggressive behavior.

Personality development: Biological theorists believe our personality is largely genetic while behavioural theorists believe it is largely influenced by our environment.

Mental illness: There are certain mental disorders that are caused by genetics from certain chemical imbalances in the brain. Examples include autism, schizophrenia, bipolar disorder, etc. While there are other mental illnesses that can be caused by toxins absorbed from the environment, and others some from particular life experiences. For example, post traumatic stress disorder (PTSD).

Race and gender: Jenson (1969) found that the average I.Q amongst black Americans was much lower compared to white Americans, leading him to theorize that intelligence is 80% inherited. This experiment caused many controversies because it demonstrated that there were natural inequalities between different social groups. His claims would be looked further into and many environmentalists would claim that the results he acquired were due to his inbuilt bias when experimenting. While others largely believe that the results he acquired were simply due to the fact that people born in an environment where their access to educational resources and privileges are limited, would score lower than others with a lot of access and opportunities. This experiment sparked many debates relating to gender as well, people question whether many differences between male and female were inborn or as a result of social and cultural conditioning.

Interactions of nature with nurture

As science progresses we recognize that many traits and behaviours do not come from just nature or nurture but rather a unique combination of both. Even though there are still areas where this debate is ongoing we can recognize that many traits are a result of a combination of the two.

Psychopathology tells us that a genetic predisposition and specific environmental factors work together to trigger a variety of mental disorders to develop in a person. This is called the diathesis stress model. Many mental disorders may be genetically inbuilt but the manifestation of them comes from an intricate working of multiple environmental factors.

Epigenetics is another emerging scientific research area that tells us that certain genes can only be expressed through environmental stressors. This means a person may have a certain genetic sequence that makes them easily susceptible to depression but without certain environmental factors put in place the person may never experience depression. Researchers have been experimenting on ways we can make epigenetic changes to individuals’ genes. Some of those ways include DNA methylation, where methyl groups are added to the DNA, suppressing certain genetic codes. Another one is histone modification where the proteins that DNA wraps around is modified to affect how tightly the DNA is packed. Then there is non-coding RNA where RNA molecules that regulate gene expression are placed.

Transgenerational epigenetic inheritance shows us that certain epigenetic factors can be passed down to future generations. An example of this is in holocaust survivors, where it is seen that the descendants of the survivors have shown epigenetic changes to their gene in relation to trauma response and levels of risk for PTSD. This further suggests how malleable our genetics really are to the environment and our individual experiences. (McLeod, S.)

Schools of thought in criminology

Cesare Lombroso: He believed that certain biological traits could determine the chances of a person becoming a criminal. He believed physical traits such as skull size and facial shape could determine a person’s susceptibility to criminality.

Sigmund Freud: He believed in the nurture side of things, where family and early childhood experiences influence the behaviour and criminality of an individual.

Edward Wilson: He believed that it was a mix of both biological heredity and environmental factors that worked together to influence the way in which a person behaves.

Studies, theories and genetic abnormalities

Minnesota twin study: This studied two twins that were raised separately. There seemed to be a high level of criminal behaviour found in both the twins, showing us that nature plays a significant role in the behaviour of a person.

Florida psychopathic study: This studied the brain scans of individuals incarcerated and diagnosed with psychopathy. It showed an abnormal activity in the prefrontal cortex of these individuals, which is an important section of the brain that deals with decision making and impulse control.

Cambridge study in delinquent development: Four hundred boys between the ages of eight to 32 were observed throughout their lives. This study showed us that individuals with behavioural issues in childhood and that faced environmental stressors, such as dysfunctional families, were more likely to diverge into criminal activities in their adulthood.

The MAOA gene often called the warrior gene is associated with more aggressive behavior and under certain environmental conditions may lead to more violent behaviour exhibited by the individuals with it.

Many studies have shown that high levels of testosterone can also lead to more aggressive behaviour from an individual, and this behaviour can be intensified or moderated depending on environmental factors.

Implications for criminal justice

With all that we’ve learnt on how genetics and the environment play such a huge role on an individual’s actions and behaviour, it leaves us wondering how we can handle criminals and the best way to approach justice. This leaves space to question the justice system and how it is structured. The most effective way to give justice to victims of violent crime while also taking into account the criminal that catalyzed this crime. Is there a telltale sign that lets us know a child will become a killer or is it all up to chance? Various studies show us that there might actually be a couple of traits to look out for that may cause a child to become a serial killer.

Four types of serial killers

1. Hedonistic: They gain sexual gratification from killing; they do it for the joy of the game.
2. Power and control: All about control, this can also be sexual.
3. Visionary: Psychotic, they see/hear things that make them kill.
4. Mission oriented: They kill for a particular reason, and they often kill specific people.

Characteristics of serial killers

1. Psychopathic and destructive.
2. Abused as children mostly in the family. This can be physically, emotionally, or sexually.
3. Macdonald triad predictors (arson, sadistic behaviour and bedwetting).
4. Isolation/bullying during childhood.

A child killer experiences the fantasy of killing as a defense mechanism against traumatic experiences currently happening in their reality. Whereas, adult killers relive that childhood traumatic event repeatedly, eventually turning into the aggressor.

Thought process of the child killer

1. Distorted thinking: Not thinking rationally, just wants to enjoy the act itself. Doesn’t necessarily think about the consequences of said action.
2. The motivational phase: This phase is initiated by an event that doesn’t necessarily have to be real. When this event occurs it motivates the child to go fulfill their fantasy as a way of handling or feeling in control of the situation.
3. The inner negative answer phase: This is when the child, feeling inadequate, perhaps due to their observed views of how society may deal with a situation as theirs, and wanting to feel better about themself, opts for the violent fantasies they have created as the most adequate option. For they believe to have very little other options in their line of view.
4. The external negative response phase: As a result of feeling powerless, the child desperately wants to feel a sense of power over people. They want to feel that they have control, so they opt for playing out their fantasies exactly as it is in their minds. That gives them a sense of power, and any negative responses from the outside would just reaffirm the power so they are not worried or thinking about any consequences that their actions may present.
5. The restoration phase: This is when the murder has been committed and the child starts to think clearly again. This is when thoughts of self preservation start coming through. The child starts thinking of ways they can improve the murders, ways of disposing of the victims and even ways of better selecting the victim. After this is over the child enters what is called the “cooling off” period. This is a time where the killer relieves the murder that had been committed again and again until it no longer brings them emotional gratification. This is when the killer starts feeling this emotional need to satisfy by killing and the cycle begins again. (McMillion, F. D.)

Behavioural elements of a killer

1. Imagination: Imagining actions that satisfy their needs; it slowly turns violent in the case of a killer.
2. Symbolism: Could involve keeping an item belonging to the victim to be able to relive their fantasy.
3. Ritualism: A pattern that the killer repeats in all the murders they commit.
4. Compulsion: A need to satisfy the emotional desire of the killer. There is a pattern of the killings becoming more violent as the killer kills more victims. This tells us that the killer has a need for more violence in his act to feel more satisfied.

Phases of murder execution

1. The motivational phase: There are primary and secondary motivations. Primary is the physiological need to feed their desire. While secondary is the need to feel control over the environment, the killer feels there is something wrong with the environment and it must be dealt with.
2. The criminal fantasy phase: After perceiving that everything and everyone is against them they take refuge in their fantasies. Their fantasies include them exerting control over others through violence, and they find comfort in that.
3. The mental anticipation of the effects phase: When the killer is thinking of committing the murder they are also thinking of the effects it will have, such as the power over the victim that it will grant them, further fueling their desire to commit it even more.
4. The design phase: This is the phase where the killer plans who they will kill, when and where they will do it and how they are going to go about it.
5. The execution phase: This is when the murder has been committed, the sensation that follows is what will determine whether that killer continues on this path of killing or not.
6. The satisfaction phase: The killing has occurred and the killer has executed their plan. If the satisfaction of one killing is enough the killer might never kill again, but if they feel as though they want to continue satisfying their inner desire then it will continue.

Making of a killer

1. Socio-environmental factor: These are events and the ways in which the killer is treated by society, family being the centermost determinant. The killer may feel isolated by the society or feel mistreated, which may lead to feelings of resentment and wanting control and dominance. This could also be negative influences in the child’s life, either the environment or others. The triggering events that cause a killer to kill happens very often to a lot of people, it just so happens to provoke criminal fantasies inside a killer’s mind.
2. Individual factors: The ability to process trauma and wanting to handle or exert power upon the person that caused the trauma. Also an inability to handle stress leads to creating violent fantasies in the mind.
3. Relational factor: The ability to have relationships with the people around them. A killer may be negatively influenced by a negative experience with their relationships, whether it be family, friends or partners.

These traits will appear in many individuals but it does not necessarily mean they will ever become a killer, these are just traits and behaviours that many child serial killers seem to have in common.

Other factors

There are many factors to take into consideration other than genetics that may have an effect on a child’s development and cause some to stray so far that they become killers.

A study was conducted where children were divided. One group was assigned to take omega three fatty acid supplements and the other group were deprived of it. The caretakers mentioned that the children who received the omega three fatty acids had a reduced likelihood of being violent for up to six months later. Another study also showed that consumption of omega three fatty acids reduced aggression. (Smith, A. L., & Meehan, T.)

These sorts of studies highlight that malnutrition in general leads to more aggressive and antisocial behaviour amongst children and adults alike. In the cases of child serial killers that I mentioned above, two of those children came from poverty-stricken families. This doesn’t automatically mean children that have a lack of nutrition will become killers. It simply highlights the effects and consequences that malnutrition can have on a child’s development and the people around them.

One of the cases that I mentioned above shows us that the child could’ve easily been influenced by her older boyfriend and harmful subcultures that she had joined online. Another one of the cases where the young child wasn’t properly reprimanded or penalized for their actions caused them to continue assuming they would suffer no consequences for their actions or possibly assuming what they had done wasn’t such a bad thing. Children are extremely susceptible to suggestions. The actions and words of those around them can greatly influence a child’s thinking and behaviour. We’ve seen it in examples such as the bobo doll experiment, where the children only showed aggression and violence after they had seen the behaviour around them.

Conclusion

It is indeed a frightening thing to hear every time a child is convicted of killing. It leaves people feeling hopeless and makes them wonder whether all children could become killers and how one can avoid such horrifying fates for their own children. A better understanding of the extremely diverse causes of criminality allows us to better our justice system, rehabilitation efforts and prevention of the cases in the first place. It is vital that we continue to explore and study this field of child killers and criminals. Based on all the research done and being done it is clear that it is a mixture of genetics and environmental factors that has caused the unfortunate spike in child killers around the world. Early diagnosis and intervention is crucial to reduce the likelihood of such cases occurring. It is important to spread awareness, implement genetic testing for all individuals and to properly nurture and care for all children. Though there are many other factors that can affect criminality, taking these measures can help curb it and influence the children in a positive manner, allowing the child an opportunity for a better life.

Bibliography

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Fletcher, J. (2024, September 5). Understanding how Nature and Nurture Influence Behavior. https://psychcentral.com/health/nature-versus-nurture

Smith, A. L., & Meehan, T. (2024, March 15). Nature versus Nurture: Biosocial Theories of Crime. https://griffithuniversity.pressbooks.pub/criminology-criminal-justice/chapter/nature-versus-nurture-biosocial-theories-of-crime/

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McMillion, F. D. (n.d.). Psychology of child Serial killer. https://www.cji.edu/wp-content/uploads/2019/12/Psychology_of_Child_Serial_Killer.pdf

Harvey, A. (2025, February 26). Amarjeet Sada, the youngest serial killer in history. https://allthatsinteresting.com/amarjeet-sada

Goldfarb, K. (2025, November 24). Jasmine Richardson, Jeremy Steinke, and the Richardson Family murders. https://allthatsinteresting.com/jasmine-richardson

Gordan, M. (2025, July 17). A Child of Darkness: The Chilling Case of 12-Year-Old Killer Piedad Martínez del Águila. https://mycrazysimplelyfe.wordpress.com/2025/07/17/a-child-of-darkness-the-chilling-case-of-12-year-old-killer-piedad-martinez-del-aguila/