A serial killer is defined as someone who kills three or more people in a subsequent time period with cooling down time in between. The technically aspect of this series of murder are must be separate event, shouldn't happen at a time and they are driven by a psychological thrill or pleasure. They usually don't have empathy and guilt of what they have done mostly egocentric these characters brand them as psychopaths.

These serial killers were a mask to hide their cruel face of theirs, they would appear very normal and having regular life. They do very much good work in concealing. Studying the biography of the serial killers implies 75 percent of one common aspects which is blindly ignored, past trauma like abusive parents, abusive environment in which they are brought up and problems they had faced. The study says that sociopathic behavior is something develops throughout years

History
According to historical criminologists, serial killers have existed throughout history. According to some reports, medieval serial killers inspired stories like werewolves and vampires. Liu Penguli of China, a Prince of Jidong (144 BC), was attacking slaves for sheer sport. Power was used to hide this from the king and it was exposed that he had murdered more than 80 people.

Liu Pengli was made a commoner and was banished. Between 1740 and 1840, members of the groups called Thuggee cult in India may have murdered a million of people. A cult member named Thug Behram is suspected of murdering as many as 931 people. In London in 1888, the unnamed killer Jack the Ripper, dubbed the 1st known serial killer, murdered at least 5 women and maybe more.

The metropolitan Police launched a large search and examination into him, during which they developed many current criminal investigation procedures. The golden period of serial murder in the US spanned from 1970 to 2000. The no of serial killers in the US reached in 1989 and has subsequently been dropping steadily. The increase in serial killing has been related to development, which has brought individuals closer together and provided secrecy. A famous professor in Radford University in Virginia, Blames the decrease in serial killings to the use of parole less frequently, greater forensic equipment, and people acting more carefully.

Social Victims
The fact is that the wounds they experienced in their early years of life can lead to them becoming serial killers later in life. The psychological impact of a variety of factors like family issues such as divorce, lack of communication, child abuse and isolation, lack of compassion from family members, affects one's personality, also induces additional factors like criminal genes or other biological backgrounds which are more possible to occur or stive to make an otherwise innocent person a criminal in the future. Although others may disagree with this idea, many serial killers who are assessed for mental illness provide similar information about their lives and psychological problems.

For example, Ted Bundy, a famous serial killer killed more than 100 women in his span. But the thing is he was not born murdered, "murders are made not born" "A trauma can turn things where it has no return". Of course, this does not mean serial killers are any less than criminal. It's preferable to think of it as a scientific explanation for a terrifying behavior.

 When people hear about a serial killer, first thing in their mind is, how does a normal looking person could do this? Main cause for serial killers to have behavioral disorders is their past and they become victims of their own past. Serial killers are made put of a mix of genes and environment, according to research. This indicates that it's not an either -or situation; both aspects must be present for someone to become a serial killer

Past Influence
Serial killer are victims of their traumatic childhood and genes. It's a hazardous time boom waiting to happen of a potential killer has the wrong DNA and had a bad childhood. According to criminologists, both biological and environmental factors can convert a youngster into a cold-blooded killer.

It is widely acknowledged that child abuse is more common among serial killers than in the general population. The occurrence of abuse in the people's population must be investigated in order to fully understand the occurrence of abuse with serial killers. It's worth noting that serial killers have a much higher rate of abuse than the overall population.

Environmental factors, such as hunger, social and economic stress, and a lack of education, are still among the most powerful markers of behavioral abnormalities in adulthood. Childhood abuse has long been recognized by psychologists as a potential cause for violence. According to a study, boys who are subjected to unpredictable, coercive, and harsh parenting are more likely to grow antisocial personalities and become violent offenders.

Naturally, not all abused boys turn aggressive. The thought that some variations, such as those that cause neuronal disturbance or hyperactivity in the brain, may put them at hazard for aggression is interesting but it is not, however, the only or even the primary cause. The FBI's intense study on 36 serial killers gives a broad picture.

All the offenders came from broken homes and experienced a cold, unfriendly, and harsh upbringing: 13 offenders claimed physical abuse, 23 psychological, and 12 sexual abuse as children. All of the person's relationships with their mothers were characterized by indifference, separation, lack of love and neglect. They didn't have much emotional or physical interaction.

To summarize the foregoing information, one can't argue that serial killers are not dangerous criminals, but can certainly argue that they may be victims of their own past and previous lives or lives that they did choose to live. They may have been unwitting victims of the situation they have battling since childhood.

Some Serial Killer Cases Are Stated Below:
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1. Ottis Toole and Henry Lee Lucas are friends and lovers. They killed, raped, and even cannibalized many victims. They both had a similar childhood. They were forced to dress as girls by their abusive mothers and were sexually harassed before the age of 10 regularly. Lucas even killed his mother and served 10 years in prison. The first victim Lucas assaulted was his own brother. Toole's father let his friends beat and abuse him when he was just 5 years old. His sister raped him, and his mother dressed him as a girl. The first person he killed was someone who picked him for sex work. This psychological and physical torture resulted in killings. They together killed too many to count but were convicted for 6 and 157 murders.
    
2. Aileen Wuornos' father was a sex offender who committed suicide in prison. At that point, her mother abandoned her to her grandparents. There, she was subjected to constant sexual abuse by her grandfather and was forced to carry the baby of her grandfather's friend, but the contract failed. She put her child up for adoption and left the city. She was traumatized, and to earn money for her livelihood, she turned into a prostitute. However, she then killed her clients, claiming they sexually assaulted her. She was eventually caught, and the trial resulted in a death sentence. During the trial, the analysis discovered that she was a psychopath with borderline personality disorder. She claimed that she hated humans and would kill again no matter what. The childhood cruelty she suffered made her hate humans, and the impact of her grandfather's acts was traumatizing and turned her into a serial killer years later.
    
3. John Haigh was a respected man in society and had a good mask to hide the reality. He had to live in confinement throughout his childhood, with only solitude as his companion. He experienced religious nightmares during childhood and naturally developed the habit of committing fraud, which resulted in his divorce. He went to prison many times, but his mind was fixed on fraudulent behavior. To avoid getting caught by the police for his crimes, he decided to kill the victims of his fraudulent activities. The first person he killed was Willan McSawnn in 1944. He brought him to the basement, struck his head, and dumped him into a drum filled with sulfuric acid, which he then dumped into a maintenance hole. This is the reason he was known as the "acid murderer." He murdered around 9 people.
    
4. Mary Bell's mother was a prostitute, so she grew up watching her mother. Her mother put her into prostitution when she was too young to understand. She was sexually and physically abused, neglected, and isolated from her family. These incidents triggered her, and at the age of 11, she killed young boys. The childhood experiences were vital reasons for her actions. The trauma of being abused made her express her frustration on others who were weaker than she was. The sociopathic mentality is usually triggered by traumatic experiences, which she faced in her childhood.
    
5. Pedro Filho was hurt in his skull when he was in his mother's womb, as his father beat his mother. The constant exposure to this kind of violence made him irrational and turned him into a psychopath. He was brought up in a harsh society and was triggered to kill his father, as his father had killed his mother. He killed more than 71 people in his lifetime and killed 4 more even after his conviction.
    
6. Edmund Kemper was a person with an IQ of 145, but he was traumatized by his mother, who blamed him for her divorce and locked him in the basement. Having rage towards his mother, he wished to kill her and took his frustration out on animals. He killed his family and many women, claiming he wanted to see how it felt. This man was very bright and intelligent, but the way his mother treated him turned him like this.
    
7. Donald Gaskins got the nickname "Wee Pee" for being smaller in size than his own age. He was a victim of abuse and neglect. He wasn't raised in a normal family. Being the son of a single mother, he saw his mother dating many men who used to beat and abuse him. He had nightmares and was a bedwetter. These traumatic childhood experiences led to him developing an obsession for killing. He killed over 100 victims, both men and women. It was called the "Coastal Kills."
    
8. Wayne Gacy became a serial killer after dressing up as a clown named Pogo for children's parties. He killed 33 men and boys. Gacy was convicted by lethal injection in 1994. Gacy's dad was an alcoholic who violently abused all of his children. One of Gacy's first memories is of being struck with a broomstick across the skull until he passed out. Gacy began to have blackouts in 4th grade, and when his father visited him in the hospital, he called him a sissy and a mama's boy.
    
9. Pedro Lepoz murdered 80 girls according to the records, though he claims to have killed 300 girls. His parents exiled him from the family when he assaulted his sister. After being on the street for a few days, he was taken by a man to an abandoned warehouse where he was assaulted. Later, he was taken to an orphanage where male teachers assaulted him. Due to the assaults he experienced during his childhood, he developed a habit of finding pleasure in torture and assaulted girls in his area. He was arrested for the murder of 80 girls.
    
10. Albert Desalvo, known as the Boston Strangler, killed 13 women. He grew up witnessing his mother being tortured by his father on a daily basis. He was impacted by that and started torturing animals to release his rage. This action escalated to killing women. Though there is a rumor that he isn't the actual killer.
     
11. Richard Ramirez was a cold-hearted murderer. His parents were busy all the time, so he stayed with his sadistic cousin who bragged about sexually assaulting women during his time in the Vietnam War. His father also subjected him and his siblings to constant beatings and abuse. These experiences in childhood resulted in his sadistic ideology. He later became a Satanist and killed 13 victims. He would break into houses, assault the occupants, and then kill them.
     
12. Andrei Chikatilo killed 53 people. He was born during famine caused by Joseph Stalin. He and his family did have much food to eat and had to eat leaves and grass to survival. His brother was kidnapped at age of 4 and was cannibalized. That was too traumatic for him to suffer. This shock and rough childhood made him adopt pleasure by killing others. He killed them and mutilated their bodies and that gave him the name "The Butcher".

There many serial killers story that matches the below description. They tend to develop this interest because of their past.

Conclusion
No one is born criminal in this world. Thing that happens to be is their circumstance and surrounding or harsh childhood the suffered. All these serial killers have one thing in common is lack of love and compassion. The all were deprived of love and safe family and surrounding to grow up. they are result of their parents and families' failure.

If they had a chance of having someone to love them and somebody and kept them safe, they would have been normal. The rage the hold and suppress within themselves causes all this. No matter of explanation they are still criminals but the safe and normal childhood while growing up will prevent from creating more serial killers.

References:

1. Merryweather C. Serial Killers Who Had the Childhood from Hell, visited on 10 Dec 2021
2. Lois Parshley, Can Your Genes Make You Kill?, visited on 11 Dec. 2021
3. Burgess, A, Sexual homicide: A motivational model. Journal of Interpersonal Violence, 1(3), 251–272. last visited March 19 2023
4. Mark Oliver, Henry Lee Lucas: The Depraved Serial Killer Who Confessed to Hundreds of Murders, last visited March 19 2023
5. Richard Stockton, How Aileen Wuornos Became History's Most Terrifying Female Serial Killer, last visited March 21 2023
6. Brianna's blog, Serial killer #3: John George Haigh aka The Acid Bath Murderer, last visited March 23 2023
7. Andrei Tapalaga, Mary Bell: The Eleven Year Old Serial Killer Even the mind of a child can be corrupted by the evil, last visited March 23 2023