Biological explanation

• What are the two explanations for genetics?

  Twin and adoption studies - criminals inherit a gene 
• What’s the twin study?

  -Christiansen (1977) - 3500 twin pairs in Denmark

  -CR for offender behaviour 35% vs 13%

  -suggesting behaviour and underlying predisposing traits are inherited
• What’s the adoption studies ?

  -Crowe (1972)

  -biology leads to a 50% risk of having a criminal record by the age of 18 vs 5%
• What was Tiihonen et als study on candidate genes?

  Genetic analysis of 800 offenders 

  -abnormalities of 2 genes 

  -MAOA - controls dopamine and seretonin in the brain and is linked to violent crimes 

  -CDH13. - substance abuse and ADHD

  -5-10% of all severe violent crimes in Finland is attributable to the MAOA and CDH13 genotypes.
• What’s the diathesis stress model?

  -environment would moderate the influence of genes

  -with schizophrenia a bio predisposition to crim behaviour could be triggered by environ factors e.g  criminal role models or a dysfunctional environment 
• Prefrontal cortex 

  Their is evidence that suggests neural differences between criminals and non-criminals 

  -lots of research on APD

  -reduced emotional responses,lack of empathy,impulsive,needing stimulation etc
• What did raine et al report about the prefrontal cortex?

  -Reported several brain imaging studies showing reduced activity in the prefrontal cortex in people with APD 

  -Raine et al also found an 11% in grey matter in the prefrontal cortex
• Mirror neurons 

  Active when we are performing or watching someone else perform

  Intentions and emotions of other people - experience empathy - switched on by default 
• What did Keysers et al found ?

  Only when criminals were asked to empathise did their empathy reaction activate.People with APD can experience empathy but do more sporadically and by choice
• Evaluation point for genetic exp ?

  :) support for diathesis stress model - mednick et al - 13,000 adoptees 

  :( twin studies assume they have equal environments 

  :( problematic due to late adoptions
• Evaluation point for neural exp ?

  :) research support between crime and the frontal lobe - kandel and freed - frontal lobe and antisocial behaviour 

  :( other factors that could contribute to APD and leading to offending - Farmington et al (2006) studied males who scored highly on psychopathy - raised by convicted parents 

  :( criminality is too complex to reduce to a genetic or neural level e.g things seem to run in families such as poverty  - CR in twin studies are never 100%.