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Psychological and psychiatric explanations of criminality


Psychiatry and psychology can explain crime, account for criminal behavior, and treat the criminal. Historically psychiatry and psychology have been intertwined with the development of law. Medicine, and its later subdiscipline, psychiatry, was particularly involved in helping to advance the concepts of guilty intentions (mens rea) and responsibility for the criminal act itself (actus reus), thereby refining the insanity and diminished responsibility defenses. As knowledge developed and the law became more sophisticated, distinctions were made between those criminals with a mental illness or those who were born with a mental impairment (now termed “learning disability”). Psychology, in particular through its work on personality disorder, introduced the idea that psychopathic behaviors that were aggressive or seriously antisocial while carried out rationally nonetheless contributed to diminished responsibility. Dominant among the preoccupations of psychiatry has been diagnosing and classifying mental illness while psychology has a wider brief, engaging in aspects of the investigation and prosecution of crime as well as searching for causes and treating offenders. The questions for psychiatry have centered on how mental incapacities come about (organically, genetically, constitutionally, dispositionally) and how to assess or measure their symptoms to help decide whether an individual acted rationally or irrationally in order to determine what to do with them (imprison or hospitalize). As medical experts, psychiatrists have assisted the courts where the insanity defense has been argued. In terms of treatments, should such a defense prevail, early interventions were segregation from other prisoners, physical restraint. Later, surgical treatments and the inducing of shock prevailed, while in the 20th century the discovery of psychotropic drugs served as a great breakthrough. Psychology emerged from a philosophical tradition likewise in the 19th century. Psychologists have only lately been employed to provide expert evidence in the courts. As psychology’s focus is more toward behavior and personality (and also deals with non-mentally disordered offenders), their role in courts often have to do with competency assessments while interventions tended to be designed to improve reasoning, social skills, or adjustments in thinking in order to facilitate re-incorporation into society. Psychologists also were instrumental in developing psychometric and other measures to predict risk of future criminal behaviors or recidivism. Both psychiatry and psychology have broader remits than purely an interest in crime, thus the term “forensic,” meaning “of the courts” identifies that particular concern such that forensic psychiatry and forensic psychology have developed as specialisms within their parent disciplines. A theme of this bibliography is to reflect the differences in approach between psychiatry and psychology. In doing so reference will be made to pioneers, key cases, and also the role played by institutions, notably Bedlam, the York Retreat, and Broadmoor, in the development of theory and practice.

Psychological Theories

When Amy goes to visit Rory, she’s reminded of all the differences between them. He’s in jail for a violent crime and doesn’t even feel sorry. It’s like he doesn’t really understand that what he did was wrong.

Psychological theories of crime say that criminal behavior is a result of individual differences in thinking processes. There are many different psychological theories, but they all believe that it is the person’s thoughts and feelings that dictate their actions. As such, problems in thinking can lead to criminal behavior. Take Rory, for example, he doesn’t believe that what he did was wrong, which was what led him to act out in the first place.

There are four basic ideas when it comes to psychological theories of crime. These general assumptions are that crime is a result of:

1. Failures in psychological development

Some people run into trouble because they didn’t develop, or grow, the way that others normally do. For example, Rory has an underdeveloped conscience. Whereas Amy hears a little voice inside her reminding her what is right and wrong, Rory just does what he wants and doesn’t think about right or wrong. This is an example of what happens when someone has an issue with psychological development.

2. Learned behaviors of aggression and violence

If someone is surrounded by violence and aggression, they are more likely to become violent and aggressive themselves, because they have learned that those behaviors are okay. For example, Rory comes from a very abusive household, and his violent parents taught him that it’s normal to work out your frustrations by being violent against others.

3. Inherent personality traits

There are some characteristics that criminals tend to share with each other, and some psychologists believe that there are certain personality traits that predispose someone towards criminal behavior. For example, even as a baby, Rory liked to seek out dangerous and exciting activities. Amy is happy to stay at home with a book; that’s enough excitement for her. But, Rory likes danger, which could lead him to act recklessly and perhaps in criminal ways.

4. Relationship of criminality to mental illness

Some people with psychological disorders end up committing crimes. While this isn’t the case for all people with mental illness, there is a higher-than-normal percentage of criminals with mental illness. For example, Rory has been diagnosed with a personality disorder, which means that he feels less empathy than other people.

All of these psychological factors could have an effect on someone like Rory, who then ends up a criminal.


Amy is wondering if psychological theories of crime could explain why her friend Rory ended up a criminal, whereas she ended up a law-abiding citizen. There certainly seems to be a lot of psychological differences between the two of them. Could that explain the differences in their behavior?

Though there is much support for psychological theories, there are also some criticisms. For one thing, opponents point out that psychological theories can’t explain why some people are criminals and others aren’t. For example, not everyone with mental illness ends up a criminal, and not everyone who was abused ends up a criminal. But, Rory, who was abused and has a psychological disorder, ended up a criminal. Psychological theories can’t tell us why that is true.

Another issue with psychological theories of crime is that they are difficult to test. Amy can’t open up Rory’s head and see his psychological issues carved on his brain. All a person can see are the symptoms of a psychological problem, not the underlying issue. This could lead to misdiagnoses and even lead to some people faking psychological disorders in order to get a lighter sentence.

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Finally, treatment plans based on psychological theories are not always effective. There is still a high rate of criminals who commit crimes even after being treated for psychological issues. Thus, even though psychological theories might be correct in judging why people become criminals, they haven’t yet figured out how to prevent people from becoming or continuing to be criminals.

Lesson Summary

Criminology is the study of crime and punishment. Psychological theories of crime look at how differences in people’s thoughts and feelings can lead to criminal behavior. There are four basic aspects of psychological theories of crime, which say that crime is a result of failures in psychological development, learned behaviors of aggression and violence, inherent personality traits, and the relationship of criminality to mental illness. Though there is a lot of support for psychological theories of crime, there are also some criticisms, including the idea that they can’t explain why some people are criminals and others aren’t, even when they have the same issues; they are difficult to test; and that treatment plans based on psychological theories are not always effective.

Learning Outcomes

When you finish watching the video, you should understand how to:

  • Recall the definition of criminology
  • List the four basic psychological theories of crime
  • Discuss the criticisms of the psychological theories of crime

Biological Theories of Crime

By Charlotte Nickerson, published Jan 10, 2022

  • Biological theories of crime, which encompass a lineage of thinking dating to the 19th century, argue that whether or not people commit crimes depends on their biological nature.
  • Some individuals are predisposed to crime because of genetic, hormonal or neurological factorsMay be inherited (present at birth) or acquired (through accident or illness).
  • No one can be a ‘born criminal’ because crime is socially defined. A link has to be made from some more general factor like aggression, impulsivity, risk-taking etc.
  • Early biological theories of crime drew influence from Darwin’s theory of evolution and natural selection. Theories such as degeneration theory posited that people who used certain poisons — such as alcohol and opium — acquired morally degenerate traits, and these traits could be passed on biologically and socially to their offspring.
  • Historically, biological theories of crime — in particular, the work of Lombroso and B.A Morel — have been used as justification for eugenic programs such as those carried out by the Third Reich.
  • The formulation of neuroscience in the latter half of the 20th century brought genetic studies of crime to light. These studies investigate how certain neurotransmitters, or chemicals in the brain, interact with a number of environmental behaviors to produce criminal behavior. One common methodology for this is twin adoption studies.

History and Overview

Biological theories of crimes state that whether or not people commit crimes depends on their biological nature. The biological characteristics that biological theories of crime claim are associated with criminality could include factors such as genetics, neurology, or physical constitution.

Although many modern biological theories of crime consider the effect of contextual and environmental conditions (what criminologists call biosocial theories), biological theories of crime distinguish themselves from sociological theories in their focus on internal factors. Biological theories of crime developed in parallel to their sociological counterparts.

Forensic biology first became a science in itself in Italy in the 19th century, with Cesare Lombroso as its founding father. Lombroso developed the concept of the “born criminal” under the influence of both phrenology (a now-defunct study of the features of the skull as indicative of mental capacity and character traits) and Darwin’s theory of evolution.

Although criminologists often paint biological theories of crime in opposition to sociological ones, Lombroso was influenced by the work of French crime statisticians such as André-Michel Guerry and Adolphe Quetelet. These crime statisticians recorded the number and distribution of crimes by collecting and analyzing statistical data, producing connections between age, gender, social origin, and crime.

These statistics pointed to the hypothesis that crime was the result of environmental and social factors as well as biological ones. His students would lean more heavily into this hypothesis, producing integrated biosocial theories of crime.

Lombroso’s criminal theory developed a large following in the German-speaking world. One remnant of this following was the so-called degeneration thesis, promoted by the criminologist Emil Kraeplin. According to the degeneration thesis, criminals pathologically and hereditary deviated from a regular genetic type. However, this genetic type could only be identified by psychological, rather than physical, characteristics.

Both the Weimar Republic and the Third Reich would use the atavistic and degeneration theses as justification for so-called “racial hygiene” projects. Thus, the Third Reich branded many ethnic minorities as genetically criminal and inferior; people to whom every right could and must be denied.

Representatives such as Franz Exner and Edmund Mezger drew scientific justifications from the twin studies of Johannes Lange, Friedrich Stumpfl’s genealogical research, and other studies that argued that criminality could only be explained by human genetic predisposition.

The Nation Socialists (that is, the Nazi Party), also drew influence from purely physiological theories of crime, such as Ernst Kretchmer’s theory of consitituion. The physiological abnormalities leading to crime, according to Kretschmer, could be in the brain or skull as well as in the structure of the body.

Because of their fatal consequences in the Nazi regime, biological theories of crime largely lost their scientific significance after the Second World War. Most criminal biologists have abandoned the idea that delinquency can be explained only by biological deviations in the offender, preferring approaches that combine biology and sociology. Terrie Moffit’s Two-Path theory is such an example.

Degeneration Theory (1857)

Degeneracy Theory, an offshoot of 19th century research into biological theories of crime, argues that certain (lower) social classes and races were predisposed to neurological and mental illnesses by inheritance, making them more likely to commit crimes.

Those in low social standing, such as prostitutes, criminals, the poor, and those with mental illnesses, were morally defective and represented a regression in human evolution. B.A. Morel (1857) proposed the first theory of progressive degeneracy in his book, Traits des Dégénérescences Physiques, Intellectuelles et Morales de l’Espèce Humaine.

Morel believed that the use of specific substances such as hashish, alcohol, and opium resulted in progressive physical and moral deterioration that would get passed on from one generation to the next, resulting in a society with both a worsened intellectual and moral character as well as certain physical characteristics.

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This theory would come to influence Cesare Lombroso’s biological theory of crime. Another key aspect of degeneration theory is the idea that moral degeneracy is heritable. Degeneration theorists widely believed that the moral and physical pathologies leading to low social status would persist and proliferate from generation to generation biologically and socially.

Thus degeneration theorists believed that the so-called “miscegenation” between morally-defective people should be regulated by eugenics and moral hygiene for the good of society.

Atavistic Theory of Crime (1876)

Cesare Lombroso (1876) was most famous for developing the avastic theory of crime in his book, The Criminal Man. In this book, Lombroso argued that there is a distinct biological class of people prone to criminality.

Lombroso’s (1876) theory of criminology suggests that criminality is inherited and that someone “born criminal”‘ could be identified by the way they look.

He suggested that there was distinct biological class of people that were prone to criminality. These people exhibited ‘atavistic’ (i.e. primitive) features. Lombroso suggested that they were ‘throwbacks’ who had biological characteristics from an earlier stage of human development that manifested as a tendency to commit crimes.

Connected to the idea of atavistic characteristics is the idea of degeneration. According to Lombroso, offenders have certain physical and mental characteristics of primitive humans, and they commit crime because of these biological abnormalities.

Credit: Wellcome Library, London. Wellcome Images [email protected] Six figures illustrating types of criminals Printed text L’Homme Criminel Lombroso, Cesar Published: 1888

Lombroso claimed that criminal types were distinguishable from the general population because they looked different. These people have atavistic, or primitive, features.

Thieves had expressive faces, manual dexterity, and small, wandering eyes; murderers had cold, glassy stares, bloodshot eyes, and hawk-like noses; sex offenders carried thick lips and protruding ears; and female criminals were shorter, more wrinkly, had darker hair and smaller crimes than normal women.

This meant, Lombroso argued, that criminals were at a more primitive stage of evolution than non-offenders, making them unable to fit into contemporary society and thus prone to committing crime. This came with the implication that criminality was heritable.

Sheldon Somotypes Theory (1942)

William Sheldon (1942) proposed a strong correlation between personality and somatotype (i.e. physique).

From a study of several hundred male physiques he derived three made body types:

  1. The ectomorph, characterized by a thin, wiry frame.
  2. The endomorph, heavy and rounded.
  3. The mesomorph, with a solid, muscular frame.

Sheldon Somotypes Theory (1942)

Each body types was associated with a particular personality:

  1. Ectomorph = introvert, quiet, fragile, sensitive
  2. Endomorph = relaxed, sociable, tolerant, peaceful
  3. Mesomorph = aggressive, assertive, and adventurous.

Sheldon noted that the vast majority of criminal were mesomorphs. One explanation for this is that a solid muscular person becomes involved in crime at an early age due to their intimidating appearance.

This biological theory may seem implausible, but people often stereotype others on characteristics such as their appearance.

Certain individual’s (e.g. the police) may make “snapshot” judgments about people which may have implications for criminal behavior.

Terrie Moffit’s Two-Path Theory (1993)

Terrrie Moffit’s Two-Path theory is a biosocial theory of crime. Moffit (1993) proposes that there are two groups of people who commit crimes: life-course-persistent offenders, whose anti-social, criminal behavior begins in childhood and continues to worsen thereafter, and adolescence-limited offenders, whose antisocial behavior begins in adolescence but ends in young adulthood.

While life-course-persistent offenders are rare but pathological in nature, adolescent-limited offenders are relatively common, temporary, and near the normal. Moffit’s two-path theory has had important implications for criminal policy, as one of the most widely received modern criminological theories.

Notably, those who follow Moffit’s theory believe that about 5% of the population could be life-course-persistent offenders. The government of Hamburg, Germany, in response to this theory, has screened primary-school age children in an attempt to provide social therapeutic measures that could possibly compensate for poor parental support.

Modern Biological Theories of Crime

Modern biological theories of crime focus specifically on how different regions of the brain are responsible for thoughts, emotions, and behaviors, and how the dysfunction of these regions can cause criminality (Raine, 2008; Viding et al., 2005; Newsome, 2014).

Neurological Theories of Crime

Neural explanations look at the structure and functioning of the central nervous system.

There are several regions of the brain that criminologists and neurologists have focused on in modern biological studies of crime. The cerebral cortex makes up the outer part of the brain, and is divided into left and right hemispheres. Each hemisphere has four lobes.

Criminologists have focused on the frontal lobe in their biological theories of crime because the region is involved in abstract thought, planning, goal formation, sustaining attention and concentration, self-monitoring, and behavioral inhibition (Moffit, 1990; Ishikawa and Raine, 2003).

Raine et al. (1997) carried out a study of 41 violent of murderers and found reduced activity in the prefrontal cortex and the limbic system of these offenders compared with control non-criminals.

Individuals with Antisocial Personality Disorder (psychopathy) display a decrease of emotional response and lack of empathy with others. These symptoms have been found in many offenders.

Brain imaging studies have found reduced activity in the prefrontal cortex of individuals with APD. Additionally, Raine et al. (2000) found a reduced volume of grey matter in this region in the brain of these individuals.

Neuroscientists also study how chemicals in the brain known as neurotransmitters can work to influence thought, emotion, and behavior. For example, some studies have shown that excessive levels of dopamine may be related to aggressive and criminal behaviors, and antipsychotic drugs that reduce dopamine may also be used to reduce aggression.

Similarly, scientists have found that increased levels of norepinephrine can result in aggressive behavior, and reduced levels can lead to antisocial behavior. These results suggest that both high and low levels of norepinephrine can result in behavioral problems. Another neurotransmitter of interest to biological theories of crime is serotonin, an inhibitory neurotransmitter used throughout the brain, including in the limbic system and frontal cortex.

Researchers have determined that reduced levels of serotonin are linked to criminal behavior, and that the neurotransmitter manages impulsivity (Brizer, 1988; Raine, 2008).

Genetic Explanations

Genetic explanations of crime propose that genetic factors could predispose individuals to commit crimes because genes code for physiological factors such as the structure and functioning of the nervous system and neurochemistry.

As in early biological theories of crime, criminologists have used family, adoption, and twin studies in estimating the extent to which certain traits are heritable (Plomin, 2004). In these studies, if the behavior of an individual is more similar to those of their biological relatives than their adopted ones, then this indicates that a trait is more influenced genetically than environments.

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In one such study by Mednick, Gabrielli, and Hutchings (1984), criminologists examined 14,427 adoptees and their biological and adoptive families to determine genetic and environmental influences on criminal behavior. The study’s results indicated that 13.5% of adoptees for whom neither adoptive or biological parents had been convicted of a crime were convicted. 14.7% of those for whom only their adoptive parents had been convicted became convicts.

These numbers spiked when the biological parents had been convicted of a crime. 20% of those whose biological parents had been convicted became convicted, and 25% of those for whom both biological and adoptive parents had become convicted became convicted (Mednick, Gabrielli, and Hutchings, 1984).

These results suggest that the traits that lead to criminality are somewhat heritable, but those who are reared in an environment where they are exposed to criminal behavior are even more likely to engage in it themselves (Newsome, 2014). More recent criminality adoption studies have supported these findings.

Rhee and Waldman (2002) conducted a review of twin and adoption studies and found that there are substantial genetic and environmental influences on antisocial behavior.

Specifically, the researchers found that about 32% of the variation in antisocial behavior is due to additive genetic effects, 9% due to nonadditive genetic effects, 16% due to environmental influences shared by the twins, and 43% due to unique environmental influences not shared by the twins.

After Rhee and Waldman, Moffitt (2005) conducted a review that concluded that about 50% of the population’s variation in antisocial behavior was due to genetic influence.

Gene-Environment Interactions

Those with dissimilar genes are likely to act differently in the same environment. Those who have genetic predispositions towards criminality are more likely to engage in criminal behaviors if they are exposed to environments conducive to criminality.

In contrast, those that do not have criminal dispositions are unlikely to engage in criminal behavior, even when they are in a criminogenic environment. Scientists such as Caspi et al. (2002) have found evidence for how criminological genes themselves interact with the environment.

Caspi et al.’s study revealed that genetic variants of a gene that produced an enzyme that breaks down neurotransmitters such as serotonin and dopamine did not have a direct effect on behavior normally.

However, boys who experienced maltreatment as children as well as having a gene that codes for low enzyme production were more likely to have antisocial behavior problems than those who did not have this gene (Kim-Cohen et al., 2006; Caspi et al., 2002).

Limitations of Modern Biological Theories of Crime

Biological genetic studies are limited because they cannot determine which specific genetic factors lead to behavioral differences. Many genes can disrupt normal development, resulting in abnormal behavior. To find out which genes could be related to antisocial and criminal behavior, scientists have conducted molecular genetic studies.

Criminologists have been interested in two types of genes: the genes that control dopamine and those that control serotonin. The varying levels of dopamine in the brain can result in a wide range of behaviors, and variants in the genes that control dopamine can lead to serious and violent antisocial behavior (Comings et al., 2000).

There are also a number of genes that code for the production, detection, and removal of serotonin in the brain, and research has indicated that low levels of serotonin is associated with increases in antisocial behavior (Raine, 2008).

The biological approach is socially sensitive as it has consequences for the legal system and society as a whole. If offending is genetic then people should not be considered responsible for their crimes, however this then leaves an important decision to be made as to what is to be done with these dangerous offenders.

Based on this theory, crime prevention measures could include genetic testing of the public but once individuals carrying genes predisposing to crime what do we do with these individuals?

About the Author

Charlotte Nickerson is a member of the Class of 2024 at Harvard University. Coming from a research background in biology and archeology, Charlotte currently studies how digital and physical space shapes human beliefs, norms, and behaviors and how this can be used to create businesses with greater social impact.

How to reference this article:

Nickerson, C. (2022, Jan 10). Biological Theories of Crime. Simply Psychology.

APA Style References

Brizer, D. A. (1988). Psychopharmacology and the management of violent patients. Psychiatric Clinics of North America, 11(4), 551-568.

Caspi, A., McClay, J., Moffitt, T. E., Mill, J., Martin, J., Craig, I. W., … & Poulton, R. (2002). Role of genotype in the cycle of violence in maltreated children. Science, 297(5582), 851-854.

Comings, D. E., & Blum, K. (2000). Reward deficiency syndrome: genetic aspects of behavioral disorders. Progress in brain research, 126, 325-341.

Ishikawa, S. S., & Raine, A. (2003). Prefrontal deficits and antisocial behavior: A causal model.

Kim-Cohen, J., Caspi, A., Taylor, A., Williams, B., Newcombe, R., Craig, I. W., & Moffitt, T. E. (2006). MAOA, maltreatment, and gene–environment interaction predicting children’s mental health: new evidence and a meta-analysis. Molecular psychiatry, 11(10), 903-913.

Lombroso, C. (1876). L’Uomo delinquente. Milano: Hoepli.

Lombroso, C. (2006). Criminal man. Duke University Press.

Mednick, S. A., Gabrielli, W. F., & Hutchings, B. (1984). Genetic influences in criminal convictions: Evidence from an adoption cohort. Science, 224(4651), 891-894.

Moffitt, T. (1990). The neuropsychology of juvenile delinquency: A critical review. Crime and justice, 12, 99-169.

Moffit, T. (1993). Adolescent-Limited and Life-Course-Persistent Adolescent Behaviour: A Developmental Taxonomy. Psychological Review, 100(4).

Moffitt, T. E. (2005). The new look of behavioral genetics in developmental psychopathology: gene-environment interplay in antisocial behaviors. Psychological bulletin, 131(4), 533.

Morel, B. A. (1857). Traite des degenerescences physiques, intellectuelles et morales de l’espece humaine et des causes qui produisent ces varietes maladives par le Docteur BA Morel. chez J.-B. Bailliere.

Newsome, J. (2014). Biological Theories of Crime. The Encyclopedia of Criminology and Criminal Justice, 1-5.

Plomin, R., & Spinath, F. M. (2004). Intelligence: genetics, genes, and genomics. Journal of personality and social psychology, 86(1), 112.

Raine, A. (2008). From genes to brain to antisocial behavior. Current Directions in Psychological Science, 17(5), 323-328.

Sheldon, W. H., Stevens, S. S., & Tucker, W. B. (1940). The varieties of human physique.

Sheldon, W. A. (1954). Atlas of men, a guide for somatotyping the adult male at all ages.

Viding, E., Blair, R. J. R., Moffitt, T. E., & Plomin, R. (2005). Evidence for substantial genetic risk for psychopathy in 7 year olds. Journal of Child Psychology and Psychiatry, 46(6), 592-597.



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