Gentic and neural explantions: Biological

• genetic explanations for crime suggest that would-be offenders inherit a gene or combination that predispose them to commit crime
• twin studies - genetic and Neural Explanation for crime

  Lange

  • investigated 13 MZ and 17 DZ where one of the twins in each pair had served time in prison
  • 10 of the MZ twins but only 2 of the DZ twins had co-twins who served prison time
  • genetic factors must play a predominant part in offending
• Adoptions studies - Gentic explanation for criminal behaviour

  Crowe

  • adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record buy 18
  • adopted children with a mother who had no criminal record had a risk of 5%
• Candidate genes - Gentic explanation for forgetting

  Tilhonen et al 2004

  • genetic analysis of over 900 offenders
  • revealed abnormalities in two genes that may be associated with violent crime:
  • MAOA gene - controls dopamine and serotonin (linked to aggressive behaviour)
  • CDH13 gene - linked to substance abuse and ADHD
  • individuals with high-risk combinations were 13X more likely to have a history of violent behaviour
• Diathesis-stress model - genetic explanation for criminal behaviour 


  A tendency towards criminal behaviour may come about through the combination of genetic predisposition and biological or psychological trigger
• evidence suggests that there may be a neural difference in the brains of non-criminals and criminals

  • individuals with antisocial personality disorder
• prefrontal cortex - neural explanation for crime 


  Raine

  • several dozen brain-imaging studies demonstrating that individuals with antisocial personalities have reduced anxiety in the prefrontal cortex
  • also found an 11% reduction in grey matter in people with APD
• Mirror neurons - neural explanation for criminal behaviour 


  Keyser et al

  • criminals with APD can experience empathy but it more sporadically
  • they could empathise when asked to
  • suggesting that they are not totally without empathy but may have a 'switch' that can be turned on and off
• Limitation of G/N explanations for crime: Problems with twin studies 


  Lange's research

  • poorly controlled and judgments related to zygosity were based on appearance and not DNA testing - lacking validity
  • twin studies typically involve small sample sizes and they are an unusual sample
  • most twins are reared in the same environment, which is a major confounding variable as concordance rates may be due to shared learning
• strength of G/N explanations for crime: support of the diathesis

  Mednick et al

  • 13,000 danish adoptees
  • 13.5% of adoptees were criminals who did not have biological or adopted parents who had convictions
  • Rose to 20% when either of the biological parents had convictions
  • 24.5% when both adoptive and biological parents had convictions

  suggests that environmental influence cannot be disregarded - supporting the model
• Limitation of G/N explanations for crime: Biological determinism 


  the notion of a 'criminal gene' presents a dilemma

  • our legal system is based on the premise that criminals have personal and moral responsibility for their crimes
  • only in some cases can criminals claim they are not acting under their own free will
  • this raises ethical questions about what society does with people who are suspected of carrying criminal genes, how this effects sentencing
• Limitation of G/N explanations for criminality: Biological reductionism 


  explanations that reduce offending behaviour to a genetic or neural level may be inappropriate and overly simplistic

  • criminality is complex
  • crime does appear to run in families but so do other mental and physical disorders, poverty and social deprivation
  • makes it difficult to disentangle the effects of genes and neural influences from other possible factors