4. biological explanations: genetic and neural Flashcards
what is the key term for genetics
genes consist of DNA strands. DNA produces instructions for general physical features of an organism (such as eye colour and height) and also specific physical features (such as neurotransmitter levels and size of brain structures). these may impact on psychological features (such as intelligence and mental disorder). genes are transmitted from parents to offspring (inherited).
what is the key term for neural explanations
any explanation of behaviour (and its disorders) in terms of (dys)functions of the brain and nervous system. this includes the activity of brain structures such as the hypothalamus and neurotransmitters such as serotonin and dopamine.
what does genetic explanations for crime suggest
would be offenders inherit a gene or combination of genes that predispose them to commit crime.
what research has been conducted around twin studies for genetic explanations
the importance of genes is illustrated by twin studies - the first criminal twin study investigated 13 identical (MZ) and 17 non identical (DZ) twins where one of the twins in each pair had served time in prison.
10 of the MZ twins but only 2 of the DZ twins had a co twin who was also in prison = genetic factors must play a predominant part in offending behaviour.
what research has been conducted around adoption studies for genetic explanations
research has 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 did not have a criminal record only had a 5% risk.
what research has been conducted around candidate genes for genetic explanations
genetic analysis of almost 900 offenders revealed abnormalities on two genes that may be associated with violent crime - the MAOA gene (controls dopamine and serotonin in the brain and has been linked to aggressive behaviour) and CDH13 (linked to substance abuse and attention deficit hyperactivity disorder).
within the sample individuals with this high risk combination were 13 times more likely to have a history of violent behaviour. however it must be emphasised that this research is in its infancy and has so far not been replicated.
what research has been conducted around the diathesis stress model for genetic explanations
if genetics do have some influence on offending it seems likely that this is at least partly moderated by the effects of the environment.
elsewhere we have seen how the diathesis stress model has been applied to schizophrenia. a tendency towards criminal behaviour may come about through the combination of genetic predisposition and biological or psychological trigger - for example being raised in a dysfunctional environment or having criminal role models.
what does evidence suggest about neural explanations
there may be neural differences in the brains of criminals and non criminals. much of the evidence in this area has investigated individuals diagnosed with antisocial personality disorder (psychopathy). APD is associated with reduced emotional responses and lack of empathy for the feelings of others - a condition that characterises many convicted criminals.
what research has been conducted around the prefrontal cortex for neural explanations
researchers have reported that there are several dozen brain imaging studies demonstrating that individuals with antisocial personalities have reduced activity in the prefrontal cortex - part of the brain that regulates emotional behaviour.
alongside this researchers have found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to control.
what research has been conducted around mirror neurons for neural explanations
research suggests that criminals with APD can experience empathy but they do so more sporadically than the rest of us. researchers found that only when criminals were asked to empathise (with a person depicted on film experiencing pain) 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 on and off unlike the normal brain which has the empathy switch permanently on.
what problems are there around twin studies which limits genetic explanations
early twin studies of criminality were poorly controlled and judgements related to zygosity (whether twin pairs were MZ or DZ) were based on appearance rather than DNA testing = may lack validity.
twin studies typically involve small sample sizes and twins are an unusual sample in themselves and may not represent the rest of the population. also the fact that most twins are reared in the same environment is a major confounding variable as concordance rates may be due to shared learning experiences rather than genetics.
what research support is there for the diathesis stress model of crime
major study of over thirteen thousand danish adoptees was conducted by mednick - 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 nor adoptive parents had convictions the percentage of adoptees that did was 13.5%. this figure rose to 20% when either of the biological parents had convictions and 24.5% when both adoptive and biological parents had convictions.
this data suggests that although genetic inheritance plays an important role in offending environmental influence cannot be disregarded - support for the diathesis stress model of crime.
what problems are there around adoption studies which limits genetic explanations
the presumed separation of genetic and environmental influences in adoption studies is complicated by the fact that many children experience late adoption which means that much of their infancy and childhood may have been spent with their biological parents anyway. similarly lots of adoptees maintain regular contact with their biological parents following their adoption. both of these points make it difficult to assess (from adoption studies) the environmental impact the biological parents might have had.
as well as this in the mednick study the figures quoted only applied to petty offences (such as burglary) and not violent crime = means that any conclusions drawn may not apply to more serious forms of crime.
how does biological reductionism limit the biological explanations
criminality is complex. explanations that reduce offending behaviour to a genetic or neural level may be inappropriate and overly simplistic. crime does appear to run in families but so does emotional instability, mental disorder, social deprivation and poverty. this makes it difficult to disentangle the effects of genes and neural influences from other possible factors.
it is also the case that whilst there is often a difference in concordance rates between MZ and DZ twins, MZ pairs do not show 100% concordance.
how does biological determinism limit the biological explanations
in the field of criminality the notion of a criminal gene presents a dilemma. our legal system is based on the premise that criminals have personal and moral responsibility for their crimes and only in extreme cases (such as a diagnosis of mental disorder) can someone claim they were not acting under their own free will. this raises ethical questions about what society does with people who are suspected of carrying criminal genes and what implications this may have for sentencing.
