Biological Explanations: Genetic and neural Flashcards
What do genetic explanations for crime suggest?
That would-be offenders inherit a gene or combination of genes that predispose them to commit crime.
What is the importance of genes illustrated by?
Twin studies.
What did Christiansen study?
Over 3500 twin pairs in Denmark and found concordance rates for offender behaviour of 35% for identical twin males and 13% for non-identical twin males.
What was offender behaviour checked against in Christiansen’s study?
Danish police records.
What did the data from Christiansen’s study indicate?
Behaviour and underlying predisposing traits might be inherited.
What did Crowe find?
That adopted children whose biological mother has a criminal record had a 50% risk of having a criminal record by 18 whereas adopted children whose biological mother didn’t have a criminal record only had a 5% risk.
What did Tihonen et al do?
A genetic analysis of almost 800 Finnish offenders.
What did Tihonen’s study suggest?
That two genes (MAOA and CD13) may be associated with violent crime.
What does the MAOA gene do?
Regulates serotonin in the brain and has been linked to aggressive behaviour.
What has the CD13 gene been linked to?
Substance abuse and attention deficit hyperactivity disorder.
What did Tihonen et al’s analysis find?
About 5-10% of all severe violent crime in Finland is attributable to the MAOA and CD13 genotypes.
How can the diathesis-stress model be applied to genetic explanations of crime?
A tendency towards offending behaviour may come about through the combination of genetic predisposition and a biological or psychological trigger e.g. being raised in a dysfunctional environemnt.
Evaluation of genetic explanations:
Using twin studies as genetic evidence assumes equal environemnts.
This ‘shared environment assumption’ may apply to MZ twins more than DZ twins because MZ twins look identical and people tend to treat them more similarly which affects their behaviour.
So higher concordance rates for MZ twins in twin studies may be because they are treated more similarly than DZ twins.
Evaluation for genetic explanations:
Support for the diathesis-stress model of offending.
A study of 13,000 Danish adoptees was conducted by Mednick et al.
When neither biological or adoptive parents has convictions the percentage of adoptees that did was 13.5%.
This rose to 20% when either biological parents had convictions and 24.5% when both adoptive and biological parents had convictions.
This shows genetic inheritance plays a role in offending but environmental influence is also important which provides support for the diathesis-stress model of crime.
What did Raine do?
Conducted many studies of the APD brain and reported that there are several dozen brain-imaging studies demonstrating individuals with antisocial personalities have reduced activity in the prefrontal cortex which also regulates emotional behaviour.
What did Raine and colleagues find?
An 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to control groups.
What does recent research suggest about offenders with APD?
That they can experience empathy but do so more sporadically than the rest of us.
What did Keyers find?
Only when offenders were asked to empathise did their empathy reaction activate which suggests APD individuals aren’t totally without empathy but may have a neural ‘switch’ that can be turned on and off unlike the normal brain which has its empathy switch permanently on.
Evaluation of neural explanations:
Support for the link between crime and the frontal lobe
Kandel and Freed reviewed evidence of frontal lobe damage and antisocial behaviour.
People with damage tended to show impulsive behaviour, emotional instability and an inability to learn from their mistakes.
The frontal lobe is associated with planning behaviour.
This supports the idea that brain damage may be a casual factor in offending behaviour.
Evaluation of neural explanations:
The link between neural differences and APD may be complex.
Other factors may contribute to APD and offending.
Farrington et al studied a group of men who scored high on psychopathy.
They had experienced various risk factors during childhood such as being raised by a convicted parent.
These early childhood experiences caused APD and also some neural differences associated with it e.g. reduced activity in the frontal lobe due to trauma.
This suggests the relationship between neural differences, APD and offending is complex and there may be other intervening variables that have an impact.
