Forensics - Genetic and Neural Explanations Flashcards
Define genetics in the context of biological explanations.
Genes consist of DNA strands. DNA produces ‘instructions’ for general physical features of an organism (such as eye colour, 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, i.e., inherited.
Define neural explanation in the context of biological 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 are genetic explanations for crime supported by?
Twin studies. The first criminal twin study was conducted by Lange, who investigated 13 MZ (identical) twins and 17 DZ (non-identical) twins. He found that 10 of the MZ twins in each pair had been in prison, compared to just 2 of the DZ twins. This suggests that genetic factors may play a role in offending behaviour.
What evidence for genetic explanations comes from adoption studies?
Crowe (1972) 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, compared to only 5% of those whose biological mother did not have a criminal record.
What is the role of candidate genes in offending behaviour?
Tiihonen et al. (2014) identified abnormalities on two genes associated with violent crime: the MAOA gene (which controls dopamine and serotonin, linked to aggression) and the CDH13 gene (linked to substance abuse and attention deficit disorder). Within a Finnish sample of 900 offenders, individuals with this high-risk combination were 13 times more likely to have a history of violent behaviour.
What does the diathesis-stress model suggest about offending behaviour?
Genes are only partly responsible for offending behaviour. A tendency to offend may be triggered by environmental factors, such as a dysfunctional upbringing or early childhood trauma.
What do neural explanations suggest about offending behaviour?
Neural explanations focus on brain activity and neurotransmitter systems. Evidence suggests that there may be neural differences in the brains of criminals and non-criminals. This includes abnormalities in areas such as the prefrontal cortex and levels of neurotransmitters like serotonin and dopamine.
What evidence supports neural explanations for offending behaviour?
Adrian Raine has found reduced activity in the prefrontal cortex of criminals, an area associated with regulating emotional behaviour.
Key neurotransmitter imbalances, such as low levels of serotonin, are linked to impulsive and aggressive behaviour.
Mirror neurons may play a role in empathy. Research by Keysers suggests that only when criminals are asked to empathise do their empathy reactions (controlled by mirror neurons) activate.
What is one evaluation point for genetic explanations of offending?
Early twin studies of criminality, such as Lange’s research, are criticised for poor control and for judgements based on appearance (e.g., whether twins were MZ or DZ) rather than DNA testing. Furthermore, twin studies usually involve small sample sizes and may not represent the wider population. The fact that most twins are raised in the same environment is also a major confounding variable, as concordance rates may be due to shared learning experiences rather than genetics. This undermines the validity of genetic explanations of offending.
What is another evaluation point for biological explanations?
A study of over 13,000 Danish adoptees by Mednick et al. (1984) found that 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 to 24.5% when both adoptive and biological parents had convictions. This supports the diathesis-stress model, suggesting that both genetic and environmental influence play a role in offending. This demonstrates that offending behaviour cannot be explained purely by genetics but involves environmental triggers.
What is one issue with adoption studies in explaining offending behaviour?
Adoption studies presume genetic and environmental influences are isolated. However, many children experience late adoption, which means their early environment may have been influenced by biological parents. Additionally, many adoptees maintain regular contact with biological parents, further complicating the separation of genetic and environmental factors. This makes it challenging to draw clear conclusions about genetic influences in offending behaviour.
What is an evaluation point for neural explanations of offending?
Although there is evidence of brain abnormalities in criminals, such as reduced activity in the prefrontal cortex, it is unclear whether these are the cause or effect of offending behaviour. For example, abnormalities could be the result of prolonged criminal behaviour, rather than a predisposing factor. This highlights the difficulty in establishing cause and effect in biological explanations of offending.
