Genetic Explanations

• Genetic explanations of offending behaviour suggest that offenders inherit one or more genes that predispose them to commit crime
• The genetic basis of offending behaviour has been investigated using twin studies, adoption studies and studies of individual genes
• Twin studies

  • MZ twins have been found to be more concordant for offending behaviour than DZ twins
  • This is assumed to be due to genetic factors
• Twin studies

  • Lange (1930) found the concordance rate for MZ twins was 77% and for DZ twins was 12%
• Adoption studies

  • Mednick et al. (1984) found 20% of adoptees with a biological parent with a court conviction went on to get a conviction themselves, compared to 13.5% of control adoptees
• Studies of individual genes

  • Tiihonen et al. (2014) found abnormalities in the MAOA and CDH13 genes may be associated with violent behaviour
  • Individuals with this high risk combination were 13 times more likely to have a history of violent behaviour
• Research on individual genes is in its infancy and findings have not been replicated
• The genetic explanation of offending behaviour

  Is incompatible with the way our legal system operates, where offenders are held personally and morally responsible