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Psychology of Crime: Why Do People Become Criminals?

Anne has a BSc in Applied Psychology and qualifications in counselling, CBT & mindfulness. She teaches mindfulness workshops and courses.

Psychological theories of crime

Many people have their own theories on what makes a criminal. Some of these theories are based on first hand knowledge or experience, some unfortunately may be based on racism or prejudice, and some on scientifically investigated studies.

And there are several psychological theories of crime, most of which have been shown to have a sound scientific basis. However, it is widely accepted that the reasons for crime are seldom one cause or the other, but rather a combination of some.

Biological Theories of Crime

These include genetics, hormones, brain chemistry (neurotransmitters) and brain structure and anatomy.


Because statistically more males commit crimes than females, it was proposed that this must be because of the genetic make-up of males. However, this theory has been largely discredited[1]

Twin studies and crime

But studies with twins have shown that identical twins are more likely to share criminal tendencies than non-identical (or fraternal) twins. This was the case even when identical twins were separated at birth, so environment or upbringing would not necessarily have been a factor [2].

Even so, some psychologists still believe that this is not conclusive evidence of a genetic link.[1]

Brain Chemistry.

Serotonin is a neurotransmitter in the brain that affects mood, which in turn can affect criminal behavior. Testosterone, the male hormone, is linked to levels of aggression. Omega 3 has been shown to lower levels of aggression, and poor nutrition before the age of 3 has also been linked to higher levels of aggression. All of these come under the heading of Brain Chemistry and all have a link to criminal behavior.

Brain Structure and Anatomy:

The part of the brain associated with or emotions is called the Amygdala (am-ig-d-la). It is believed that damage to the Amygdala can have an effect of criminal behavior. [3] This may be because the person concerned would have a limited fear and conditioning response, thus fear of punishment would not deter them from committing a crime.

The Hippocampus is where we store our memories. Damage to this area could mean we do not remember being punished for our crimes, and so would commit them again and again.

The Frontal Cortex, as the name suggests, is to the front of our brain and would also appear to be involved, among other functions, with our self control-as one famous case-study showed:

Phineas Gage.

The most famous case of brain damage causing a change in self-control is one of a man called Phineas Gage. In 1848, Phineas was a mild-mannered and conscientious railroad worker foreman in Vermont, U.S. He was overseeing the laying of explosives one fateful day. It was the practice to lay sand over the explosives in a hole and then to tap it down with a tamping iron. Phineas was using the tamping iron, which was 3’8” long and 1.5” in diameter, when a spark ignited the explosive and sent the tamping iron straight through his left cheek and out through the frontal cortex, landing several feet behind him. Incredibly, Phineas not only survived, but walked to the cart which was to transport him to a doctor.

Actual Skull of Phineas Gage. Bottom left is the tamping iron shown beside the skull.

Actual Skull of Phineas Gage. Bottom left is the tamping iron shown beside the skull.

"No Longer Gage"

While Phineas later appeared to have made a full recovery, those who knew him before the accident said that he was “No longer Gage” No longer mild mannered and conscientious, he became verbally aggressive and abusive, unreliable in his work and impatient and impulsive to the extent that the railroad company could no longer employ him.

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Was it the brain damage that caused the change?

It appeared that the damage to the frontal cortex caused the change in Phineas. However, it must also be remembered that brain damage also has the potential to cause depression, and that there was also a possibility that Phineas would have suffered from Post Traumatic Stress, either of which could also cause changes in his personal disposition.

Socialisation theories of crime

These include Learning Theories such as:

  • Classical Conditioning-the famous example being Pavlov’s Dogs, in which Pavlov trained the dogs to salivate at the sound of a bell.
  • Operant Conditioning-The Skinner Box, developed by B.F Skinner (who else?) in which he trained rats to press (or ‘operate’) levers in order to get to their food.
  • Observational Learning-“Monkey see-Monkey do”

But humans are not dogs, rats or monkeys. However, it would seem that we do learn by similar methods. If a child is surrounded by crime, either within the family or the community, they are likely to learn criminal behaviour by any or all of the above methods.

A child can learn to get what he wants by other means. (This child is an actor and is now an adult-picture printed with his permission)

A child can learn to get what he wants by other means. (This child is an actor and is now an adult-picture printed with his permission)

Routine Activity Theory

This can tie-in somewhat with Learning Activity; for example, if a child learns that stealing is one way to get what they want, they will do it again. All they need is for three elements to be in place:

1.Motivation: They want something

2.Suitable Target: They see what they want

3.Absence of Guardians: And there’s no one about

They get away with it, and do it again and again, until it becomes routine [4].

Strain Theory:

This is probably one of the best known psychological theories of crime.

A person really wants something, such as material goods, a better lifestyle or even an education, but they can see no possible way of ever achieving it now or in the future. This understandably causes dissatisfaction, perhaps even resentment against the people who do have what they want.

But then they see there is a way to achieve their desires through stealing, drug dealing or other criminal behaviour [5].

Control Theory:

A Marxist theory, which says that the Criminal Justice System is seen as being developed by the dominant classes to the sole advantage of the dominant classes, causing resentment and rebellion. [6]

An ambulance is not penalised for breaking the speed limit.

An ambulance is not penalised for breaking the speed limit.

Social Construction Theory of Crime

Each society has their own view of what is and is not a crime: For example, in Saudi Arabia, public displays of affection are illegal.

Circumstance can also change whether certain behavior is a crime or not. For example, a Police car or an Ambulance may break the speed limit without suffering a penalty.

Society’s view of crime can also change with time; for example, Prohibition, Homosexuality, and more recently, Cyber crimes.

Just some of the theories

These are just some of the more well-known psychological theories of crime.

If you want to learn more, I suggest you consult any good textbook on forensic or criminal psychology.

Meanwhile, take a look at the video below for Rational Choice theory..


[1] Howit, D., (2009), Introduction to forensic and criminal psychology (3rd ed) Harlow, UK, Pearson Education.

[2] Viding, E., Blair, R. R., Moffitt, T. E., & Plomin, R. (2005). Evidence for substantial genetic risk for psychopathy in 7-year-olds. Journal Of Child Psychology & Psychiatry, 46(6), 592-597. doi:10.1111/j.1469-7610.2004.00393.x

[3] Raine, A. (2008). From Genes to Brain to Antisocial Behavior. Current Directions In Psychological Science (Wiley-Blackwell), 17(5), 323-328. doi:10.1111/j.1467-8721.2008.00599.x

[4]Clarke, R. V., & Felson, M. (1993). Routine activity and rational choice. Piscataway, NJ US: Transaction Publishers

[5] Agnew, R. (1993). Why do they do it? An examination of the intervening mechanisms between "social control" variables and delinquency. Journal Of Research In Crime & Delinquency, 30(3), 245-266.

[6] Bonger, W. (1916) Crime and Economic Conditions. Boston. Little Brown.

Questions & Answers

Question: What factors create a criminal?

Answer: There is seldom just one factor, rather a combination.

Question: What causes brain damage?

Answer: There is not just one cause of brain damage. It can be caused by an accident, a difficult birth, a birth defect, a disease or other causes.

Question: Why is it that siblings can be in the same environment and one shows a high level of criminality and the others do not?

Answer: As mentioned in the article, there are many theories of why someone becomes a criminal, but it is generally agreed that it is a combination of genes, events, conditioning, and personality. It has been shown in studies with twins that identical twins are more likely to share criminal tendencies than non-identical (or fraternal) twins. This might indicate a genetic link, as identical twins have more genetic similarities, but also that personality is involved, in the case of the fraternal twins. There also is a theory that where siblings come in the family can have an effect on their behavior. For example, middle children often show more challenging behaviors and it's theorized that it is because they are trying to get attention. I'm not a forensic psychologist, so that is about the limit of my knowledge.


Grace on May 08, 2019:

I completely agree with this article. This subject fascinates me because it proves that everyone is human and we all have different reasons for the way we act, good or bad, therefor proving that no one was born a monster. I believe that the biggest factor on why criminals are the way they are and the way they think, has to do with their home life. Everyone's home is different. Some good, some average, some bad and some terrible. Either way, young kids/adults will react to these situations differently. Kids that are abused or bullied in their home will feel unloved and rejected, therefor causing them to lash out on something. All people are different though. It is a slow going process but it dosen't just happen over night. It can take a few years, a whole life time and then they suddenly snap. They've contained their rejection and past thru many years but one day someone could hit a pressure point and then they loose it. I don't think people know how much they can really affect people's emotions or thinking. We might be the crack that breaks the ice. For instance if a girl is abused as a child or young adult she will have ill feelings to the person that abused her. If that person were to be her father, she would grow up hating her father, and men in general. Right or not. Later on if a man upsets her in a specific way to her, she will then be even more outraged by men. I'd say one of the biggest factors in why people act the way they act is based on how/where they grew up. Some kids though triumph thru their hard past and learn to be independent and grow from those hardships, while some may take those to heart and keep it with them for the rest of their life.

Hannah on November 29, 2018:

Thyroid also can contribute to criminal behavior. .high T3 - low T4 can be a big factor in the make up of criminal behavior. Hyperthyroid..coupled with perhaps , other influences ,lend to criminal behavior . Tyroid balance is essential for whats to be considered a normal thought pattern .... though a chemical in balance of the thyroid can be the sole factor to very aggressive criminal behavior .

Mohit on March 09, 2018:

Japan is the almost crime free country now so no theory work for them, I think a perfect social system works a criminal mind people..

Odhiambo Reagan on September 13, 2017:

How can you relate and apply sociology in criminology and security studies

Florence Emily on January 18, 2017:

This is a very interesting article. I completely agree with many of these topics and theories. One theory I suggest that I regard quite highly is the patronization of young children in the domestic home. I often find that when older children or verging teenagers are patronized, it invokes in them the response of resentment and inferiority, It also undermines their intelligence, especially whereby they are prone to feeling outbursts of rage at these indictments. Furthermore, being the youngest of five myself, I often feel uncontrolled rage and have a fabulous temper because of this. I therefore feel that in addition to these other theories, people might consider the simple act of how we show respect to children and what effects this may have on their feelings? I also thank you for this blog, it was very helpful in the construction of a project I have been working on.

annerivendell (author) from Dublin, Ireland on February 08, 2015:

Hi Ifeanyi, Thank you for your comment. Apologies for taking so long in replying: As far as I know, Phineas Gage lived for about 11 years after the accident. He worked in various jobs, but eventually developed severe epilepsy and died during a seizure. Interestingly, since writing this hub, I came across another article which disputed that Gage remained unreliable and unsociable ( Best of luck with your study.

ifeanyi on January 28, 2015:

thanks for ur thought ,,,,,this hub is really a development to my study and so fascinating.....

please i wana know how many years phineas gage lasted on that brutal condition//????thanks

annerivendell (author) from Dublin, Ireland on October 17, 2014:

Hi Salmon. What do you need to know, besides what's in the hub? I don't have any crime figures, if that's what you're looking for. Sounds like a fun project. Best of luck with it.

Salmon on October 15, 2014:

Hello. My class is doing a project on changing the world! I chose crime because that's mostly what I talk about (apart from Zombies, Chainsaws and Bloody Murders but anyhow) I would like to learn some more basic facts on crime please help! Laterz Salmon out!

annerivendell (author) from Dublin, Ireland on January 29, 2014:

Sorry I only saw this commnet now, Cennai! Yes, I agree that family environment has been shown to bea contributing factor in crime.

mathira from chennai on November 18, 2013:

Lack of good family life also can make people turn towards violence as they have not experienced love or emotional security. Good hub, annerivendell.

annerivendell (author) from Dublin, Ireland on October 04, 2012:

I absolutely LOVE TEDtalks! There hasn't been a boring or even indifferent speaker yet. As for poor Phineas Gage-remember that trephination was reputed to take place regularly at one time, (referred to in Philip Pullman's fantastic Trilogy, His Dark Materials, as Treepanning) and they've found skulls to "prove" it! Thank you for your comment.

Elliott Ploutz from Las Vegas, Nevada on October 03, 2012:

Gah. Phineas Gage. I was always really wary of his story, like you. It's not good to base theories on one popular example. However, I did hear that they found similar effects in other brain damaged and lobotomized individuals.

If you haven't heard of it already, I want to tell you about TEDtalks! It's about experts in the field who talk about their research. There's an entire section on criminal psychology, theories, and sociology. I think you might find it interesting.

Interesting hub!

annerivendell (author) from Dublin, Ireland on October 01, 2012:

Thank you, Nettlemere. Yes, Phineas Gage is an amazing story. If you put his name into any search engine you'll get plenty of information. We learned about him in Freshman year Psychology, but I did remember hearing something about him before that.

Nettlemere from Burnley, Lancashire, UK on September 30, 2012:

That tamping iron through the skull is phenomenal. Poor chap.

Very interesting hub and well evidenced hub.

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