biological explanations to crime: genetic and neural Flashcards
what is the main assumption of a genetic explanation
suggests that would-be offenders inherit gene/genes that predispose them to commit crime
what have twin studies shown about the biological basis to crime
more genetically similar an individual is to a criminal, the higher the concordance rate for committing a crime, therefore a genetic predisposition makes it more likely a person will turn to crime.
outline a twin study that demonstrates the genetic basis to crime.
Christiansen studied over 3500 twins in Denmark and found concordance rates for offending behaviour of 35% for MZ and 13% for DZ.
outline an adoption study that demonstrates the genetic basis to crime.
Crow found that adopted children whose biological mother had 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 has been found about candidate genes and crime
two genes may be associated with violent crime. MAOA (regulates serotonin in the brain and has been linked to aggressive behaviour). The CDH-1 gene has been linked to substance abuse and ADHD. a combination of genes can create a genetic vulnerability to crime therefore crime is polygenic.
(AO3) outline a study that demonstrates that specific genes are linked to crime
Tiihonen et al conducted a genetic analysis of 800 Finnish offenders, found that about 5-15% of all severe violent crime is attributable to the MAOA and CDH-13 genotypes that results in the phenotype of violent behaviour, substance abuse ect.
outline the diathesis stress model of crime
A tendency towards offending behaviour may come about through the combination of genetic predisposition and biological or psychological trigger e.g. being raised in a dysfunctional environment or having criminal role models.
what is the neural assumption about crime
-Evidence suggests that there may be neural differences in the brains of criminals and non-criminals. This evidence as involved individuals diagnosed with antisocial personality disorder - reduced emotional response, lack of empathy
Outline a study that supports a neurological difference in the brain of a criminal (AO3)
Raine conducted many studies of the APD brain, these demonstrate that individuals with APD have reduced activity in the prefrontal cortex (regulates emotional behaviour). Found an 11% reduction in volume of grey matter in prefrontal cortex compared to controls. Also found APD had a reduced autonomic response.
what are some neurological differences criminals may have?
reduced activity and volume of grey matter of the prefrontal cortex (emotional behaviour regulation)
reduced activity in the amygdala, needed for emotional processing.
mirror neurons in criminal brains need to be activated to function - may not be permenantly on/firing resulting in a lack of remorse +empathy
what neurotransmitters have been implicated to crime and what do they regulate
dopamine + serotonin - involved in mood regulation, reward system, impulsivity and aggression.
What did Keysars find about mirror neurons in individuals with APD
only when offenders were asked to empathise did their empathy reaction (controlled by mirror neurons) activate. suggesting they may have a neural switch that can be turned on and off unlike the ‘normal’ brain, which has the empathy switch permenantly on.
(AO3) how does Christiansen’s study support a genetic explanation to crime
The higher concordance rate for MZ twins must be due to a genetic factor as they share 100% of their genes. Un addition we would expect half the concordance rate for DZ twins as they only share 50% which is demonstrated through the concordance rate of 13% for DZ. this shows a genetic predisposition in some individuals makes it more likely a person will turn to crime.
(AO3) how does Christiansen’s study lack support for gentic explanation.
If crime purely due to a genes we would expect 100% concordance for MZ. never found which would suggest an alternate explanation may account for the 65% that were not found to have a concordance rate. EG stress diathesis model - interactionist model. Perhaps 35% is due to shared environment needed to trigger criminal behaviour, whereas 65% did not have same experience.
Why are twin studies not always the most valid (AO3) -genetic
MZ twins share same environment both pre and post birth. Often treated the same due to similar looks by others, this will affect their behaviour. Therefore shared environment may contribute to increased concordance rate in MZ compared to DZ. Perhaps crime is due to both biology and environment, in reality it is difficult to separate.