Forensics: Biolgoical Explanations: Genetic And Neural Explanations Flashcards
what are genes
- consist of DNA strands
- DNA produces ‘instructions’ for general physical features of an organism
- genes are inherited by our parents
What is the genetic explanation for crime
- would be offenders, inherit a gene, or combination of genes, that predispose them to commit a crime
How do twin studies illustrate the importance of genetic explanations of crime
- lange conducted the first criminal study who investigated 30 (MZ) and 17 (DZ) twins where one of each twin had served time in prison
- 10 of the MZ twins and only 2 of the DZ twins had a co twin who was also in prison
- so genetic factors must play a predominant part in offending behaviour
How do adoption studies illustrate the importance of genetic explanations for crime
- Crowe - found adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record by 18
- adopted children whose mother didn’t have a criminal record only had a 5% risk
How do candidate genes illustrate the importance of genetic explanations of crime
- Tiihonen et al - conducted a genetic analysis of almost 900 offenders
- revealed abnormalities on 2 genes that may be associated that may be associated with violent crime: MAOA gene - (controls dopamine and serotonin in the brain + is linked to aggressive behaviour) and CDH13 gene (linked to substance abuse and ADHD)
- individuals with this ‘high risk’ combination were 13x more likely to have a history of violent behaviour
How does the ‘diathesis stress model’ illustrate the importance of genetic explanations of crime
- this theory argues that if genetics do have an influence on offending, it is moderated by the effects of the environment
- a tendency towards criminal behaviour may come about through the combination of genetic predisposition and biological or physiological trigger
What is the ‘neural explanation’ for crime
- evidence suggests there may be neural differences in the brains of criminals and non criminals
- most evidence in this area has investigated individuals diagnosed with antisocial personality disorder
- APD is associated with reduced emotional responses, lack of empathy etc and is common in criminals
outline research into the ‘prefrontal cortex’ as a neural explanation for crime
- raine - has conducted studies on the APD brain, states there are many brain imaging studies that prove sufferers of APD have reduced activity activity in prefrontal cortex (meant to regulate emotional behaviour)
- raine et al found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD than the control group
outline research into ‘mirror neurons’ as a neural explanation for crime
-recent research suggests criminals with APD CAN experience empathy but more sporadically than normal
- keysers et al - found only when criminals were ASKED to empathise (with a person depicting pain on film) did their empathy reaction (controlled by mirror neurons) occur
- suggests that are not totally without empathy but have a neural ‘switch’ that can be turned on and off unlike the normal brain
What are the three evaluation points for genetic and neural explanations for crime
- problems with twin studies
- support for the diathesis stress model
- problems with adoption studies
Outline ‘problems with twin studies’ as an evaluation point for genetic and neural explanations for crime
- early twin studies on criminality (e.g. Lange) were poorly controlled and judgements related to zygosity (whether twins are MZ or DZ) were based on appearance + not DNA
- so may lack validity
- twin studies also involve smaller samples + may not be reflective of the wider population
- most twins are also raised in the same environment which is a major confounding variable
Outline ‘support for the diathesis stress model‘’ as an evaluation point for genetic and neural explanations for crime
- major study of over 13,000 Danish adoptees was conducted by Mednick et al
- researchers defined criminal behaviour as being in possession of at least one court conviction, this was checked against the danish police records for each of the adoptees
- if neither biological nor adoptive parents had convictions, percentage of adoptees that did was 13.5%
- this figure rose to 24.5% when both adoptive and biological parents had convictions
- so both genetic inheritance and environmental influences play a role in offending
Outline ‘problems with adoption studies ‘’ as an evaluation point for genetic and neural explanations for crime
- many children experience late adoption, which complicates the presumed separation of genetic and environmental influences
- so much of their infancy and childhood may have been spent with their biological parents anyway
- also, lots of adoptees maintain regular contact with their biological parents
- so it is difficult to assess, from adoption studies, the environmental impact biological parents may have had
