Biological explanations

• Risk of being diagnosed with schizophrenia

  • Individuals with an identical twin: 48%
  • Individuals with a sibling: 9%
  • General population: 1%
• Candidate genes


  Genes that have been related to schizophrenia
• Schizophrenia is polygenic
• Polygenic


  Related to a number of different genes that all confer a small increased risk
• Schizophrenia is aetiologically heterogeneous
• Aetiologically heterogeneous


  Different combinations of genes can lead to the condition
• Ripke et al. (2014) found that 108 separate genetic variations were associated with an increased risk of schizophrenia
• Biological explanations of offending behaviour: A historical approach (atavistic form)


  • Proposed by Lombroso
  • Criminals have distinguishing physical features called atavistic features from a more primitive stage of evolutionary development
  • Explains why criminals are savage, untamed, and unable to conform to the rules of modern society
• Strength of Lombroso's work

  1. Credited with shifting the emphasis in crime research towards a more scientific realm

  2. Referred to as 'the father of modern criminology'
• Lombroso did not compare his sample of criminals to a non-criminal control group
• Goring (1913) compared 3,000 criminals to 3000 non-criminals and found no evidence to support Lombroso's theory of atavistic form
• Lombroso's work has distinct racial undertones
• Genetic explanations of offending behaviour suggest that offenders inherit genes predisposing them to commit crime
• Adoption studies


  1. Offspring with biological parent with court conviction more likely to get a court conviction themselves

  2. Supports genetic explanation of offending behaviour
• Studies of individual genes

  1. Abnormalities in MAOA and CDH13 genes may be associated with violent behaviour

  2. Individuals with high-risk gene combination more likely to have a history of violent behaviour
• Research in genetic explanations of offending behaviour is in its infancy and findings have not been replicated
• Within their sample, individuals with a high-risk combination were 13 times more likely to have a history of violent behaviour
• Research in the area of offending behaviour is in its infancy and findings have not been replicated
• Problems with twin studies include the assumption of equivalent environments for MZ and DZ twins, affecting internal validity
• Problems with adoption studies include the influence of stress prior to birth on the development of the foetus, affecting internal validity
• The genetic explanation of offending behaviour is incompatible with the legal system's notion of personal and moral responsibility
• Neural explanations of offending behaviour focus on brain structure and function
• Antisocial personality disorder is characterised by impulsive, irresponsible, and often criminal behaviour
• Individuals with antisocial personality disorder may have abnormalities in the prefrontal cortex
• Individuals with antisocial personality disorder may have dysfunctional mirror neurons
• Research into neural explanations of offending behaviour

  Sample sizes are usually very small due to difficulty in accessing the target population and the time-consuming and expensive nature of brain scanning techniques, limiting generalisability and external validity
• Research into neural explanations of offending behaviour

  Can be deterministic, suggesting that neural factors alone cannot explain offending behaviour
• Research into neural explanations of offending behaviour

  Does not establish cause and effect, leaving open the possibility of reverse causation
• Neural factors alone cannot be used to explain offending behaviour


  Some individuals with neural abnormalities do not commit crime
• Research into neural explanations of offending behaviour does not establish cause and effect
• Abnormalities in the prefrontal cortex

  Could be caused by an environmental factor, such as physical abuse in childhood
• Evidence supporting Eysenck’s theory of the criminal personality: Eysenck & Eysenck (1977) found higher E and N scores in male prisoners compared to controls
• Levels of moral reasoning according to Kohlberg

  • Level 1: Preconventional morality
  • Level 2: Conventional morality
  • Level 3: Postconventional morality
• Each level of moral reasoning


  Represents a more advanced form of moral reasoning
• Cognitive distortions are errors in information processing
• Examples of cognitive distortions relevant to offending behaviour

  • Hostile attribution bias
  • Minimalisation
• Neural explanations


  Refer to the role of the brain or neurochemicals in the cause of offender behaviour
• Neural explanations


  • Reduced activity in the prefrontal cortex area of the brain is linked to offender behaviour
• genetic mutations may predisposed an individual to commit a crime. What did Price find?

  Price found a high number of violent, male criminal had an XXY chromosome pattern which led to increased levels of testorterone and increased agression. Suggestign that out genetic information does influence our behaviours, and criminal ones.
• What were the concordance rates for MZ and DZ twins for offending behaviour?

  o   The concordance rate for MZ twins was 77%

  o   The concordance rate for DZ twins was 12%