Genetic and neural explanations Flashcards
intro
• Early biological explanations from criminality have been largely discredited e.g. Lombroso
• Suggestions however have continued to be investigated - heritability of characteristics.
• Neural differences between criminals and non-criminals have also been established.
• The two could be connected
• Genetic abnormalities could lead to structural and functional differences in the criminal brain.
genetic explanations
Criminals inherit a gene.
• Twin Studies
• Christiansen (1977) - 3500 twin pairs in Denmark.
• CR for offender behaviour 35% vs. 13%
• Suggesting behaviour and underlying predisposing traits are inherited.
• Adoption Studies
• Crowe (1972)
• Biology lead to a 50% risk of having a criminal record by the age of 18 vs. 5%. (criminal mother)
candidate genes
Tihonen et al. (2014) - genetic analysis of 800 offenders
• Abnormalities on two genes.
• MAOA - controls dopamine and serotonin in the brain and is linked to violent crime.
• CDH13 - Substance abuse and ADHD
• 5-10% of all several violent crime in Finland is attributable to the MAOA and CDH13 genotypes.
diathesis stress model
Makes sense that the environment would moderate the influence of genes.
• As with schizophrenia - a biological predisposition to criminal behaviour could be triggered by environmental factors.
• E.g. Criminal role models or a dysfunctional environment.
neural explanation-prefrontal cortex
Evidence suggests neural differences between criminals and non-criminals.
• Lots of research on APD
• Reduced emotional responses, lack of empathy, impulsive, needing stimulation etc.
• Raine et al. reported several brain imaging studies showing reduced activity in the prefrontal cortex in people with APD.
• Raine et al. also found an 11% reduction in grey matter in the prefrontal cortex.
neural explanations-mirror neurons
• Mirror neurons active when we are performing or watching someone else perform
• Intentions and emotions of other people → experience empathy.
• Switched on by default.
• Keysers et al. (2011) found that only when criminals were asked to empathise did their empathy reaction activate.
• People with APD can experience empathy, but do so more sporadically and by “choice”
s-genetic explanations
Support for the diathesis stress model.
* Mednick et al. (1984) conducted a study on over 13,000 adoptees.
* It was found that when neither the biological nor adoptive parents had convictions the percentage of adoptees that did was 13.5% 20% when either of the biological parents did | 25% when both sets of parents did.
Inheritance plays a role but environment cannot be disregarded.
L-adoption and twin studies
Problems with Twin Studies
• Twin studies assume equal environments - because the twins are raised together.
This could however apply much more to MZ than DZ twins → people (parents) tend to treat them more similarly
• Impacts behaviour.
• Higher concordance rates could be a result of being treated the same, rather than due to genetics.
Problems with Adoption Studies
• Separation of genetic and environmental influences is problematic due to late adoptions.
• Adoptees often maintain regular contact with their biological parents.
• This makes it tricky to assess the relative impact of biology.
• This suggests that assessing the relative impact of nature and nurture may only be possible with very early adoptions where contact with biological relatives does not occur..
Eval neural explanations
Brain Evidence
• Research support for the link between crime and the frontal lobe.
• Kandel and Freed (1989) reviewed evidence of frontal lobe damage and antisocial behaviour.
• Impulsive behaviour | emotional instability | inability to learn from mistakes.
Supports the idea that brain damage may be a causal factor in offending behaviour.
Intervening Variables
• Other factors could contribute to APD and ultimately to offending.
• Farrington et al. (2006) studied males who scored highly on psychopathy.
• Raised by convicted parents, physically neglected → could have also caused neural differences e.g. Due to trauma.
• Relationship is complex and there are possible intervening variables.
Issues and debates
Biological Reductionism
• Criminality is too complex to reduce to a genetic or neural level.
• Lots of things seem to run in families e.g. poverty, emotional instability, social deprivation.
• It is difficult to disentangle all of the possible influences.
• Furthermore CR in twin studies are never 100% - environmental factors may be responsible or at least partly responsible for criminal behaviour. The diathesis-stress model could be used to explain criminal behaviour where concordance rates for MZ twins are not 100%
6 marker
Genetic explanations suggest that offenders inherit genes that predisposes them to crime. Whereas neural explanations suggest that offenders brains are in someway structurally different to the brains of nonoffenders.
The role of genes has been investigated via twin studies, adoption studies, and also genetic analysis.
Christiansen (1977) studied 3500 twin pairs in Denmark and found concordance rates for offending behaviour of 35% for identical twins and 13% for non-identical twins, suggesting some genetic influence. Furthermore a genetic analysis conducted by Tihonen et al. (2015) in Finland suggested that the MAOA and CDH13 genotypes are linked to violent crime. The analysis further suggesting that between 5% and 10% of all violent crime in Finland can be attributed to these genotypes.
Research into neural explanations has focussed on antisocial personality disorder, symptoms of which include a lack of empathy and reduced emotional responses. APD characterises many convicted offenders and Raine et al. reported reduced activity in the prefrontal cortex of people with APD and also found an 11% reduction in grey matter in the prefrontal cortex (a part of the brain that regulates emotional behaviour compared to controls.
