bio explanations: genetic & neural Flashcards
what do genetic explanations for crime suggest
would-be offenders inherit a gene/s that predispose them to commit a crime
types of genetic explanations
- twin & adoption studies
- candidate genes
- diathesis-stress model
twin studies research
karl christiansen 1977
describe twin studies research
- 3500+ twin pairs in denmark
- found concordance rates for offender behaviour were 35% in MZ males & 13% for DZ males
- lower for females
- all twins born 1880-1910 in region of denmark
- offender behaviour checked against danish police records
what does the twin studies data suggest
not just behaviour inherited but underlying predisposing traits
MZ twins
monozygotic = identical
DZ twins
dizygotic = non-identical
adoption research
raymond crowe 1972
describe adoption research
- found adopted children with biological mother who had criminal record = 50% risk of having criminal record by 18
- compared to 5% risk for adopted children whose biological mother doesn’t have criminal record
candidate genes research
tiihonen et al. 2015
describe candidate genes research
- genetic analysis of ~800 finnish offenders
- two genes (MAOA & CDH13) associated with voilent crime
- MAOA gene regulates seretonin & linked to agressive behaviour
- CDH13 gene linked to substance abuse & attention deficit hyperactivity disorder (ADHD)
- found 5-10% of all voilent crime in finland attributable to MAOA & CDH13 genotypes
describe diathesis-stress model
- genetic influence on offending partly moderated by effects of environment
- tendency towards offending behaviour may arise from combination of genetic predisposition & biological/psychological trigger
- eg. raised in dysfunctional environment, criminal role models
idea for neural explanations
neural differences in brains of offenders & non-offenders
where is much of the evidence for neural explanations from
antisocial personality disorder (APD)
= reduced emotional responses, lack of empathy & condition which characterises many convicted offenders
(neural) research on prefrontal cortex
adrian raine
(lot of studies on APD brain)
(neural) describe research on prefrontal cortex
- reported there’s several dozen brain-imaging techniques showing individuals with APD have reduced activity in prefrontal cortex
- prefrontal cortex = regulates emotional behaviour
- raine & colleagues (2000) found 11% reduction in grey matter in prefrontal cortex of those with APD vs. controls
(neural) research on mirror neurons
christian keysers 2011
(neural) describe research on mirror neurons
= recent research suggests those with APD can experience empathy but more sporadically
research (keysers 2011)
- when offenders asked to empathise = empathy reaction (controlled by mirror neurons) activate
- suggests APD individuals not totally without empathy but may have neural ‘switch’ to turn on/off
genetic AO3: (-) issues with twin evidence
P: a limitation of using twin studies for genetic evidence is the assumption of equal environments
E: twins being studied may not have experienced constant environmental factors growing up. this ‘shared environment assumption’ may apply more to MZ twins than DZ twins as MZ twins appear identical so people (especially parents) will treat them more similarly which impacts their behaviour
T: thus, higher concordance rates for MZ twins may be due to their similar treatment compared to DZ twins
genetic AO3: (+) support for diathesis-stress
P: research support for diathesis-stress model
E: study of 13,000 danish adoptees by mednick et al. (1984) where neither biological/adoptive parents had convictions, percentage of adoptees which did was 13.5% (quite high). this rose to 20% when either of biological parents had convictions & 24.5% when both adoptive/biological parents had convictions
T: shows genetic inheritance plays role in offending but environmental factors clearly influence also which provides support for this model
EXTRA genetic AO3: (+/-) nature v. nurture
(+) it’s presumed adoption studies (eg. mednick et al.) are good way of separating nature v. nurture & if crime has genetic component, then adopted child should still experience influence of biological parent (without living with them)
(-) however, many adoptions occur when they’re older & so, spend several years with biological parents. also, many adoptees encouraged to maintain contact with biological families so exert environmental influence
neural AO3: (+) brain evidence
P: support for link between crime & frontal lobe
E: kandel & freed (1989) reviewed evidence of frontal lobe damage (incl. prefrontal cortex) & antisocial behaviour. people with damage often showed impulsive behaviour, emotional instability & inability to learn from mistakes. frontal lobe associated with planning behaviour
T: supports idea that brain damage may be causal factor in offending behaviour
neural AO3: (-) intervening variables
P: link between neural differences & APD is complex
E: other factors may contribute to APD & thus, offending. farrington et al. (2006) studied group of men who scored high on psychopathy (APD). they had experienced various risk factors in childhood eg. raised by convicted parent, physically neglected etc. it could be argued that these early experiences caused APD & some of neural differences associated with it eg. reduced activity in frontal lobe from trauma (rauch et al. 2006)
T: suggests relationship between neural differences, APD & offending is complex as may be many intervening variables which impact it
EXTRA neural AO3: (+/-) biological determinism
- biological approach suggests offending behaviour determined by genetic/neural factors which aren’t controlled by individual. thus, they shouldn’t be held responsible for crime.
- however, our justice system is based on notion that we all have responsibility for our actions. only in extreme circumstances (eg. mental disorder) is individual judged to lack responsibility. the identification of possible biological precursors to crime complicates this principle
