4. biological explanation: genetic and neural

what does the genetic explanation suggest

for crime, it suggests that offenders inherit a gene, or a combination of genes, that predispose them to commit crime

aspects of the genetic explanation

• twin adoption studies

• candidate genes

• diathesis stress model

research on twin adoption studies

christiansen studied over 3500 twin pairs in denmark

• found concordance rates for offender behaviour of 35% for MZ twin males and 13% for DZ males

• rates were slightly lower for females

• offender behaviour was checked against police records

suggests its not just the behaviour that may be inherited but the underlying predisposing traits

candidate genes research

tiihonen studied almost 900 offenders

• found abnormalities on two genes that may be associated with violent behaviour - the MAOA gene and CDH13 gene

• those with this combination were 13x more likely to have a history of violent behaviour

• 5-10% of all severe crime in finland is attributed to these genotypes

MAOA and CDH13 gene roles

MAOA - controls dopamine and serotonin in the brain, linked to aggressive behaviour

CDH13 - linked to substance abuse and ADD

diathesis stress model

diathesis = genetic predisposition ie inheriting genes from criminal parents associated with aggression

stress = effects of the environment ie being raised in a dysfunctional environment

• combine to create a tendency towards criminal behaviour

evaluation

1. research support

2. issues with twin evidence

3. biological determinism BOTH

4. reductionist BOTH

research support

Diathesis stress model - study of 13000 danish adoptees found offending rates increased from 13.5% with no convicted parents, to 24.5% when both biological and adoptive parents had convictions

Twins - study of 3500 twin pairs found concordance rates for offending behaviour 35% for MZ twin males and 13% for DZ males

Candidate genes - study of 900 offenders found abnormalities on two genes associated with violent behaviour (MAOA and CDH13) attributed to 5-10% of all severe crime in finland

issues with twin evidence

• a limitation is the equal environments assumption

1. assumes MZ and DZ twins experience the same environment but MZ twins are often treated more similarly as they look identical - higher concordance rates for MZ twins may therefore be due to shared environmental experiences and not genetics

2. twin studies dont show 100% concordance for offending behaviour in MZ twins despite sharing 100% of their genes

• shows genetics alone cannot explain crime and that social or environmental factors must play a role

biological determinism FOR BOTH

• suggest criminal behaviour is the inevitable result of genetic makeup

• if a ‘criminal gene’ or ‘criminal brain’ were identified it would imply individuals have little free will and raise serious ethical dilemmas for society ie whether people should be presumptively incarcerated before commiyting a crime, or prevented from reproducing reflecting ideas with the eugenics movement

• implications are problematic as they violate human rights, ignore role of environmental factors, and assume criminal behaviour is unavoidable rather than influenced by life experiences

BUT this is addressed with the diathesis stress model, reducing determinism and providing a more ethical and socially acceptable explanation of crime

reductionist

• reduce complex behaviours like crime to simplistic biological causes

• ignore the holistic interaction of social, cognitive and psychological factors in offending

• approach lacks a full explanation for why crime occurs in specific contexts or why many people with similar biology dont offend

what is a neural explanation

any explanation of behaviour in terms of the brain and nervous system

what is APD

antisocial personality disorder

• reduced emotional responses

• lack of empathy

• lack of guilt

aspects of the neural explanation

• prefrontal cortex

• mirror neurons

prefrontal cortex research

raine

• his brain imaging research shows individuals with APD have reduced activity in their prefrontal cortex - regulates emotional behaviour

• found 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD

what are mirror neurons

they fire both in response to personal action and to the action on the part of others

research on mirror neurons

keysers

• showed criminals a film of someone getting hurt

• only when the psychologist asked them to empathise did their empathy reaction activate - controlled by mirror neurons

• suggests people with APD are not void of empathy but there is a neural switch that can be turned on and off

neural explanations evaluation

1. research support

2. intervening variables

3. biological determinism

strengths and limitations of brain imaging

research support

Raine - brain imaging research shows individuals with APD have reduced activity in prefrontal cortex which regulates emotional behaviour - 11% reduction in the volume of grey matter

Keysers - showed criminals a film of someone getting hurt and only when asked to emphasise they did (controlled by mirror neurons) - shows people with APD are not void in empathy but there is a neural switch than can be turned on and off

intervening variables

• the relationship between brain differences, APD and offending may be more complex than suggested

• farrigton found men with psychopathy often experienced childhood risk factors ie neglect or being raised by a convicted parent, rauch suggests trauma may also reduce frontal lobe activity

• these early experiences could cause both APD and neural differences so brain abnormalities may be a consequence of environmental factors rather than the original offending cause

• suggests there are intervening variables weakening claim neural differences alone explain criminal behaviour, supporting interactionist explanation