biological explanations - genetic and neural

Question 1

genetic explanations - twin and adoption studies

Answer 1

• Karl Christiansen studied over 3500 twin pairs in Denmark, found concordance rates for offender behaviour of 35% for identical twin males and 13% for non-identical twin males
• offender behaviour was checked against Danish police records
• this indicates that it may not be just the behaviour that might be inherited, but the underlying predisposing traits
• Raymond Crowe found that adopted children whose biological mother had a criminal record had a 50% risk of having a criminal record by the age of 18
• adopted children whose mother didn’t have a criminal record only had a 5% risk

Question 2

genetic explanations - candidate genes

Answer 2

• genetic analysis of almost 800 Finnish offenders suggested that two genes (MAOA and CDH13) may be associated with violent crime
• the MAOA gene regulates serotonin in the brain and has been linked to aggressive behaviour, the CDH13 gene has been linked to substance abuse and ADHD
• found that about 5-10% of all severe violent crime in Finland is attritutable to the MAOA and CDH13 genotypes

Question 3

genetic explanation - diathesis-stress model

Answer 3

• if genetics do have some influence on offending, it is likely that this is 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, such as being raised in a dysfunctional environment

Question 4

neural explanations

Answer 4

• evidence suggests there may be neural differences in brains of offenders
• much of this evidence has involved individuals with antisocial personality disorder (psychopathy)
• APD is associated with reduced emotional responses, a lack of empathy for the feelings of others, and is a condition that characterises many convicted offenders

Question 5

neural explanations - prefrontal cortex

Answer 5

• Adrian Raine conducted many studies of the APD brain, reporting that there are several brain-imaging studies demonstrating that individuals with antisocial personalities have reduced activity in the prefrontal cortex (regulates emotional behaviour)
• Raine and his colleagues also found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls

Question 6

neural explanations - mirror neurons

Answer 6

• suggested that offenders with APD can experience empathy, but they do so more sporadically than others
• Christian Keysers found that only when offenders were asked to empathise did their empathy reaction (controlled by mirror neurons) activate
• suggests that APD individuals are not totally without empathy, but may have a neural ‘switch’ that can be turned on and off, not like the normal brain which has the empathy switch permanently on

Question 7

evaluation limitation for genetic explanations - issues with twin evidence ⭐️

Answer 7

• it is assumed by researchers that environmental factors are held constant, because twins are bought up together and therefore must experience similar environments
• this may apply much more to MZ than DZ twins because MZ twins look identical and people tend to treat them more similarly which in turn affects their behaviour
• higher concordance rates for MZ twins in these studies may simply be because they are treated more similarly than DZ twins

Question 8

evaluation strength for genetic explanations - support for diathesis-stress ⭐️

Answer 8

• a study of 13,000 Danish adoptees was conducted by Sarnoff Mednick
• when neither the biological or adoptive parents had convictions, the percentage of adoptees that did was 13.5% (quite high)
• this figure rose to 20% when either of the biological parents had convictions, and 24.5% when both adoptive and biological parents had convictions
• shows that genetic inheritance has an important role in offending, but environmental influence is clearly also important

Question 9

evaluation strength for neural explanations - brain evidence ⭐️

Answer 9

• support for link between crime and frontal lobe
• Elizabeth Kandel and David 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 mistakes
• frontal lobe is associated with planning behaviour
• supports idea that brain damage may be a causal factor in offending behaviour

Question 10

evaluation limitation for neural explanations - intervening variables ⭐️

Answer 10

• other factors may contribute to APD, and to offending
• David Farrington studied men who scored high on APD
• 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 experiences caused APD and also some of the neural differences associated with it, such as reduced activity in the frontal lobe due to trauma
• suggests that relationship between neural differences, APD and offending is complex and there may be other variables that have an impact