biological explanation for offending - genetic and neural

• Lange (1930)

  • conducted a twin study
  • 13 identical- 10 co twins also had time in prison
  • 17 non-identical- 2 co twins also had time in prison
  • genetic factors must play a dominant role in offending behaviour
• Christiansen (1977) - further development of Lange's research

  • 87- identical
  • 147- non-identical
  • found a concordance rate of 33% of identical and 12% for fraternal
  • there is a genetic predisposition to crime
  • biologically deterministic
• Jari Tiihonen et al (2014) - candidate genes

  • revealed that abnormalities on two genes may be associated with violent crime
  • MAOA low activity- responsible for controlling dopamine and serotonin in the brain and have been linked to aggressive behaviour
  • CDH13 gene- regulator in neural networks, linked to substance abuse and ADD
  • with this sample, if individuals have the combination of the two, were 13 times more likely to have a history of violent behaviour
  • he concluded that there is a link between these genetic mutations and crime.
  • however, did also state that this research is in its infancy and has not been replicated
• diathesis stress model

  • genetic predisposition and biological/psychological trigger
  • epigenetics- interplay where genes are switched off, sometimes by environmental factors- maltreatment as a child or being raised in a dysfunctional environment
• neural explanation

  • evidence suggests there may be neural/structural differences in the brains of criminals
  • much of this evidence has been based on individuals diagnosed with antisocial personality disorder (APD)/psychopathy
  • this disorder has been linked with reduced emotional responses or lack of empathy for any victims of crime
• Adrina Raine

  • pre-frontal cortex
  • according to a vast sum of brain-imaging studies, there is reduced brain activity/functionality in the pre-frontal cortex of those diagnosed with APD/murderers/violent individuals
  • limbic system- this part of the brain is responsible for regulating emotion. And therefore, contributes to impulsivity and control
  • found an 11% reduction in grey matter in the pre-frontal cortex of people with APD compared to his controls
• limbic system

  • structures that impact emotion are the thalamus and amygdala.
  • Raine et al (2004)
  • studied murderers who were found not – guilty by reason of insanity in the (NGRI).
  • reduced activity levels were found in the limbic system.
• neurotransmitters

  • serotonin – low levels have been linked to predispose someone to aggression- this neurotransmitter inhibits the pre-frontal cortex.
  • noradrenalin – linked with aggression, violence and criminality – High levels of this are released during the fight or flight response/ perceived threat.
• mirror neurons

  • Christian Keysers et al (2011)
  • found that criminals with APD can experience emotions, but this happens more sporadically
  • only when criminals were asked to empathise with a person, they were watching on a film were experiencing pain, they did empathise
  • the empathetic reaction is controlled by mirror neurons
  • suggesting that criminals with APD are not totally without empathy but may have a neural switch that can be turned on an off
• evaluation of twin studies

  • Lange’s research was problematic due to only basing knowledge of MZ and DZ on appearance. Therefore, lacking control and the results may lack validity
  • twin studies typically involved small sample sizes, and therefore may not be representative of a wider population
  • twins are typically raised in the same environment, and therefore this is a confounding variable as concordance rated may be due to shared learning experiences not genetics
• Mednick et al (1984)

  • 13000 Danish adoptees
  • biological and adoptive parents- no court convictions: twins 13.5% convicted
  • biological or adoptive parents- court convictions: twins 20% involved in crime
  • both adoptive and biological parents-court convictions: 24.5% involved in crime
  • this suggests that genetic inheritance plays an important role in offending, environmental influence cannot be disregarded