Genetic and neural explanations

• Genetic explanations for crime suggest that would-be offenders inherit a gene or combination of genes that predispose them to commit crime.
• Twin and adoption studies

  • Christiansen studied over 3500 twin pairs in denmark and found concordance rates for offender behaviour of 35% for identical twin males and 13% for non-identical twin males, with slightly lower rates for females
  • Offender behaviour was checked against Danish police records, this data indicates that it is not just the behaviour that might be inherited but the underlying predisposed traits
• Adoption studies

  • Crowe found that adopted children who's biological mother had a criminal record had a 50% risk of having a criminal record by the age of 18, whereas adopted children whose biological mother didn't have a criminal record only had a 5% risk
• Candidate genes

  • analysis of 800 Finnish offenders suggested that 2 genes MAOA and CDH13 may be associated with violent crime
  • The MAOA gene regulates serotonin and has been linked to aggressive behaviour aand the CDH13 gene has been linked to substance abuse and ADHD.
  • The analysis found that about 5-10% of all severe violent crime in Finland is attributed to the MAOA and CDH13 genotype
• Diathesis stress model

  • If genetics have some influence on offending it is likely the environment does too .
  • There may be a genetic predisposition but a psychological external trigger is needed, for example being raised in a dysfunctional environment or having criminal role models
• Neural explanations

  • Offenders may have neural differences, much of the evidence has involved individual diagnosed with antisocial personality disorder
  • APD is associated with reduced emotional responses, lack of empathy so is associated with offenders.

  Amygdala

  • linked to emotions, survival instincts and memory
  • Raine- studied murderers who were found not guilty due to insanity, found abnormal activity of the amygdala and limbic system
• Pre-frontal cortex

  • Raine- brain-imaging studies suggesting that offenders have reduced activity in the pre-frontal cortex, the part of the brain that regulates mood and planning
  • Raine also found an 11% decrease in grey matter in the pre-frontal cortex in people with APD (antisocial personality disorder)
  • 8.2 % of US population have had a brain injury compared to 60% of prisoners in the US
• Mirror neurones

  • Recent research has suggested that offenders with APD can experience empathy but they have to be asked to. Empathy is controlled by mirror neurones and these only activate when asked to not naturally like the rest of us.
• A03: One limitation of using twin studies is the assumption of equal environments

  • IT is assumed that environmental factors are constant because they are usually bought up together and have similar experiences,
  • However this is much more common of MZ twins rather than DZ, because identical twins are even more likely to be treated similarly which could affect their behaviour.
  • Therefore concordance rates in MZ twins being higher may just be due to the fact they are treated more similarly than DZ.
• A03: Support for Diathesis stress

  • 13000 Danish adoptees were studied
  • When neither biological or adopted parents had convictions- children that did was 13.5%
  • 20% when either biological or adopted did
  • 24.5% when both did.
  • shows genetic inheritance plays an important role in offending but environmental influence is clearly also important, providing support for the diathesis-stress model of crime
• A03: Brain evidence

  • Research support from Kandel and Freed, people with frontal lobe damage tended to show impulsive behaviour, reduced emotions, inability to learn from mistakes.
  • The frontal lobe is associated with planning behaviour.
  • This suggests damage to frontal lobe is a factor in causing offending.
• A03: biological determinism

  • Biological approach suggests that offending is determined by genetic/neural factors which cannot be controlled by the person. So a person should not be held responsible for a crime
  • However, our justice system is based in the principle that we all have responsibility for our actions
  • Only in extreme circumstances (mental disorder) is an individual judged to lack responsibility
  • The identification of biologically determined genes complicates this principle