Bio Explanations: Genetic And Neural Flashcards
Genetic explanations propose that one or more genes predispose individuals to criminal behaviour. Evidence for this comes from twin studies where mz and dz twins are compared. Raine reviewed research on the delinquent behaviours of twins and found over 50% concordance for mz twins and only 21% for dz.
Abnormally low levels of MAOA may be the cause for this criminal behaviour. One researcher investigated male members of a Dutch family and analysed their DNA. The members of the family had histories of impulsive and violent criminal behaviours. He found that they shared a gene that led to abnormally low levels of MAOA. Another study found that abnormality in the CDH13 gene could also be a cause. Modern understanding suggests that genes are switched on and off by epigenomes which have been affected by environmental factors. One possibility is maltreatment in childhood. Researchers assessed anti social behaviour at age 26 and found 12% of those men with low MAOA genes had experienced maltreatment when they were babies but were responsible for 44% of violent convictions.
Neural explanations consider how structures of the brain may be different in criminals as well as differences in neurotransmitter levels. A common observation is that criminals report having had some head injury. 60% of the criminals in prisons have had a brain injury. Therefore brain differences could be due to nature or nurture.
Raine looked at brain imaging studies and found that murderers and psychopaths have reduced functioning in the prefrontal cortex- the area of he brain responsible in regulating emotion and controlling moral behaviour. Lowered activity in this area is associated with impulsiveness and loss of control. Limbic system- the thalamus and amygdala are linked to emotion and motivation. Raine studied murderers who were found not guilty due to insanity and compared them to matched controls. They found abnormalities in the limbic system especially the amygdala
Neurotransmitters: low levels of serotonin may predispose individuals to impulsive aggression and criminal behaviour partly because the neurotransmitter inhibits the prefrontal cortex.
Noradrenaline: both very high and very low levels of this neurotransmitter are linked to aggression and violence. High levels of noradrenaline are associated with activation of the SNS and fight or flight response and so linked to aggression. Low levels of noradrenaline reduces the ability to react to perceived threats.
A strength of the genetic explanation is that there is a lot of support from research evidence. There has been a rise in the understanding of genetics and inheritance because of the use of adoption studies. Researchers found that adopted children who had a biological parent with a criminal record had a 50% greater 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% chance.
Another study of 14000 adoptees found that 15% of sons adopted by criminal families went on to become criminals compared to 20% whose biological parents were criminals. This suggest that inherited genes are a more significant factor. However there is only a 5% difference between the two values. This difference is not large enough to determine that genes predispose certain individuals to criminal behaviour and is an explanation of offending behaviour.
Furthermore a weakness of the genetic and neural explanations is that they only explain violent crimes and not any non violent crimes. Biological explanations may just account for particular kinds of crime. Criminal behaviour is said to be a social construction so as there are many types of criminal behaviour it cannot just be explained in terms of genetics and it’s interactions with the environment. This therefore means that the approach is very reductionist and it may be invalid to generalise the findings.
A weakness of the neural explanations is that the direction of cause and effect is unclear. Abnormalities in the brain could be the cause of offending behaviour but could also be the result of it or just an intervening variable. Research only highlights a correlation between head injuries and later criminality. However it could be a spurious relationship as someone who grew up in a violent household or engages in risky behaviour might be more likely to suffer from head injury. This shows that the link between a head injury and offending behaviour could be because of a violent childhood or a preference for risk. It is highly deterministic to think a head injury could cause criminality.
An advantage of the neural explanation is that the findings can be applied to the real world.
If low levels of serotonin cause increased aggression in criminals then prisoners could be given diets high in serotonin that could enhance their serotonin levels and hopefully decrease their aggression.
