biological Flashcards
Genetics
DNA strands that produce instructions for physical features such as eye colour or brain structure and neurotransmitter levels
- May impact psychological features eg intelligence and mental disorder
- Genes are transmitted from parents to offspring
Twin studies
Karl Christiansen - over 3500 twins in Denmark
Concordance rates for offending behaviour - 35% MZ, 13% DZ
Included all twins born between 1880 and 1910 - not just behaviour that might be inherited but the underlying predisposing traits
Adoption studies
Raymond Crowe - 50% risk of criminal record for adopted children whose biological mothers had criminal record (only 5% when mothers had no record)
Candidate genes
Genetic analysis of almost 800 Finnish offenders - Tiihonen et al
MAOA gene regulates serotonin - aggression
CDH13 - substance abuse and ADHD
5-10% of all severe violent crime in Finland attributable to one of two genotypes
Diathesis-stress model
Offending behaviour is due to a combination of inherited factors and environmental influences
Genetic predisposition and biological or psychological trigger
EVAL - issues with twin evidence
P - limitation as twin studies assume equal environments
E - researchers studying twins environmental factors are held constant as twins grew up together
E - ‘shared environment assumption’ apply more to MZ than DZ as MZ look identical so people treat them more similarly
L - higher concordance rates for MZs in twin studies may simply be because they are treated more similarly than DZ
EVAL - support for diathesis-stress
P - strength as research support
E - study of 13,000 danish adoptees by Mednick et al
E - neither the biological nor adoptive parents had convictions, the percentage of adoptees that did was 13.5%. Figure rose 20% when either of biological parents had convictions and 24.5% when both adoptive and biological parents had convictions
L - genetic inheritance plays an important role in offending but environmental influence is important - support for diathesis-stress model of crime
EVAL - nature and nurture
P - nature and nurture - adoptive studies eg Mednick et al good way of separating nature and nurture
E - if crime has a genetic component - adopted child should still experience the influence of biological parent despite not living with them
E - many adoptions take place when children are older, so they spend several years with their biological parents - adoptees encouraged to maintain contact with biological family so biological parents exert an environmental influence
Neural explanation
Neural differences in brains of offenders and non-offenders
Research focus on antisocial personality disorder - reduced emotions, lack of empathy ect
Prefrontal cortex
Raine et al - people with APD (lack of empathy) have reduced activity in the prefrontal cortex
Found 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls
Mirror neurons
Keysers - people with ADP showed empathy (controlled by mirror neurons) but only when asked to - neural switch on and off
EVAL - brain evidence
P - strength as support for link between crime and frontal lobe
E - Kandel and Freed - reviewed evidence of frontal lobe damage and antisocial behaviour
E - People with such damage show impulsive behaviour, emotional instability and an inability to learn from their mistakes - frontal lobe is associated with planning behaviour
L - supports the idea that brain damage may be a causal factor in offending behaviour
EVAL - intervening variables
P - limitation is link between neural differences and APD may be complex
E - other factors may contribute to ADP - Farrington et al - studied a group of men who scored highly on psychopathy
E - These individuals had experienced various risk factors during childhood - raised by convicted parent and being neglected - early childhood experiences and neural differences associated with it such as reduced activity in frontal lobe due to trauma
L - Suggests that relationship between neural differences, APD and offending is complex and there may be other intervening variables that have an impact
EVAL - biological determinism
P - biological approach suggests that offending behaviour is determined by genetic / neural factors
E - cannot be controlled by the person - person should not be held responsible for a crime
E - however - our justice system is based on the notion that we all have responsibility for our actions
L - identifications of possible biological precursors to crime complicates this principle
