Biological explanations:Genetic and neural explanations -A-Level Psychology

Genetic explanations:

-suggests that would-be offenders inherit gene/genes that predispose them to commit crime.

Twin studies:Johannes Lange investigated 13 MZ twins and 17 DZ twins where one of the twins in each pair had served time in prison.Lange found that 10 MZ twins but only 2 DZ twins had a co-twin who was also in prison.Lange concluded that genetic factors play an important role in offending behaviour.

Adoption studies:Crowe found that adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record by the age of 18,whereas adopted children whose mother didn’t have a criminal record only had a 5% risk.

Candidate genes:A genetic analysis of almost 900 offenders by Jari Tiihonen et al revealed abnormalities on two genes that may be associated with violent crime-MAOA gene(controls dopamine and serotonin in the brain,linked to aggressive behaviour) and CDH13(linked to substance abuse).In the Finnish sample,individuals with this high risk combination were 13 times more likely to have a history of violent behaviour.This research has not been replicated.

Diathesis-stress model:A tendency towards criminal behaviour may come about through the combination of genetic predisposition and biological or psychological trigger e.g. criminal role models.

Neural explanations:

-Evidence suggests that there may be neural differences in the brains of criminals and non-criminals.

-Much of the evidence in this area has investigated individuals with antisocial personality disorder which is associated with reduced emotional responses,lack of empathy for the feelings of others.This condition characterises many convicted criminals.

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

Mirror neurons:Recent research suggests that criminals with APD can experience empathy but they do so more sporadically than normal people.Christian Keyders et al found that only when criminals were asked to empathise did their empathy reaction (controlled by mirror neurons in the brain) activate.This suggests that APD individuals are not totally without empathy,but may have a neural switch that can be turned off and on,unlike the normal brain which has the empathy switch permanently on.

Evaluation:

Problems with twin studies-early twin studies were poorly controlled and judgements related to zygosity were based on appearance rather than DNA testing,so may lack validity.Twin studies also have a small sample size.Most twins are reared in the same environment which is a confounding variable as concordance rates may be due to shared learning experiences rather than genetics.

Support for the diathesis -stress model of crime-Sarnoff Mednick et al studied over 13000 Danish adoptees.The researchers defined criminal behaviour as being in possession of at least one court conviction and this was checked against Danish police records for each of the adoptees.When neither the biological and adoptive had convictions ,13.5% of adoptees had convictions.This figure rose to 20% when either of the biological parents has parents,when both adoptive and biological parents had convictions 24.5% of adoptees had convictions.This shows how genetic inheritance has an important role in offending and how environmental influence can not be disregarded.