Genetic and neural explanations of crime Flashcards
What are genetic and neural explanations of crime?
Genetic explanations for crime: Suggest that offenders inherit a gene, or combination of genes, that predispose them to commit crime.
Neural explanations for crime: Any explanation of crime in terms of (dys)functions of the brain and nervous system. This includes the activity of brain structures such as the hypothalamus and neurotransmitters such as serotonin and dopamine.
Who is good support for this
Stephen Mobley
- 1991 shot manager of Domino’s pizza
- 1994 arrested + sentenced to death
- Family history: four generations of his family (which included uncles, aunts and grandparents) had been responsible for a range of violent and criminal acts – including rape and murder.
- Mobley’s attorneys appealed his sentence on the basis that he had inherited a ‘criminal gene’ and could not be held responsible for his actions - not accepted and died 2005
- However, in Italy a man committing murder had his sentence cut by a year after the judge learned he had a mutated MAOA gene linked to aggression.
Genetic explanations to offending
TWINS
P - The importance of genes is illustrated by twin studies.
E - For example, Christiansen (1977) studied over 3,500 twin pairs in Denmark and found concordance rates for offender behaviour of 35% for identical twin (MZ) males (with slightly lower rates for females) and 13% for non-identical twin (DZ) males. This included all twins born between 1880 and 1910 in a region of Denmark. Offender behaviour was checked against Danish police records.
E - This data indicates that it is not just the behaviour that might be inherited but the underlying predisposing traits.
Crowe (1972) found that adopted children whose biological mother has 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.
DIATHESIS STRESS
Although genetics have some influence on offending, it seems likely that this is at least partly moderated by the effects of the environment.
A tendency towards offending behaviour may come about through the combination of genetic predisposition and biological or psychological trigger - for example, being raised in a dysfunctional environment or having criminal record role models.
CANDIDATE GENES
- Analysis of 800 Finnish offenders suggested that two genes MAOA and CDH13 = associated with violent crime
- The MAOA gene regulates serotonin in the brain and has been linked to aggressive behaviour and the CDH13 gene has been liked to substance abuse and ADHD.
- The analysis found that about 5-10% of all severe violent crime in Finland is attributable to the MAOA and CDH13 genotypes
EVALUATION of genetic exp
EVALUATION OF TWIN EVIDENCE - issues
P - One limitation with using twin studies as genetic evidence is the assumption of equal environments.
E - It is assumed by researchers studying twins that environmental factors are held constant because twins are brought up together and therefore must experience similar environments. However, this ‘shared environment assumption’ may apply much more to MZ twins than DZ twins because MZ twins look identical and people tend to treat them more similarly, which, in turn, affects their behaviour.
E - Therefore higher concordance rates for MZs in twin studies may simply be because they are treated much more similarly than DZ twins.
EVALUATION OF DIATHESIS STRESS- SUPPORT
P - One strength is support for the diathesis-stress model of offending.
E - A study of 13,000 Danish adoptees was conducted by Sarnoff Mednick et al. (1984). When neither the biological nor adoptive parents had convictions, the percentage of adoptees that did was 13.5%. This figure rose to 20% when either of the biological parents had convictions, and 24.5% when both adoptive and biological parents had convictions.
E - This shows that genetic inheritance plays an important role in offending, but environmental influence is clearly also important, providing support for the diathesis-stress model of crime.
Neural explanations to offending
Raine has conducted many studies of the APD brain, reporting that there are several dozen brain-imaging studies demonstrating that individuals with antisocial personalities have reduced activity in the prefrontal cortex, the part of the brain that regulates emotional behaviour. Alongside this, Raine found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls.
APD is associated with reduced emotional responses, a lack of empathy for the dealing of others and is a condition that characterises many convicted offenders.
Recent research suggests that offenders with APD can experience empathy but they do so more sporadically than the rest of us. Keysers found that only when offenders were asked to emphasise did their empathy reaction controlled by mirror neurons activate. This suggests that APD individuals are not totally without empathy but may have a neural ‘switch’ that can be turned on and off, unlike the ‘normal’ brain which has the empathy switch permanently on.
Evaluation of neural explanation
EVALUATION - BRAIN EVIDENCE
P - One strength of the neural explanation is support for the link between crime and the frontal lobe.
E - Kandel and Freed reviewed evidence of frontal lobe damage and antisocial behaviour. People with such damage tended to show impulsive behaviour, emotional instability and an inability to learn from their mistakes. The frontal lobe is associated with planning behaviour.
E - This supports the idea that brain damage may be a causal factor in offending behaviour.
EVALUATION - INTERVENING VARIABLES
P - One limitation is the link between neural differences and APD may be complex
E - Other factors may contribute to APD and ultimately to offending. Farrington et al. studied a group of men who scored high on psychopathy. These individuals had experienced various risk factors during childhood, such as being raised by a convicted parent and being physically neglected. It could be that these early childhood experiences caused APD and also some of the neural differences associated with it - such as reduced activity in the frontal lobe due to trauma.
E - This suggests that the relationship between neural differences, APD and offending is complex and there may be ther intervening variables that have an impact.
