Inherited criminality Flashcards
Where can we see evidence for the genetic component for criminal behaviour?
Twin studies where MZ and DZ twins are compared.
What research did Raine (1993) review? What did he find?
Research on the delinquent behaviour of twins.
Found 52% concordance rates for MZ twins compared with 21% for DZ twins.
What two genes have been linked to criminal behaviour?
MAOA.
CDH13.
What did Brunner et al analyse? What did they find?
The DNA of 28 males members of a Dutch family who had histories of impulsive and violent criminal behaviours.
Found that the men shared a particular gene that led to abnormally low levels of MAOA.
What was Tiihonen’s sample? What did they find?
900 offenders.
Found evidence of low MAOA activity and also low activity from the CDH13 gene.
They estimated that 5-10% of all violent crime in Finland is due to abnormalities in these two genes.
What is diathesis-stress in terms of epigenetics?
Current thinking in terms of epigenetics proposes an interplay where genes are “switched” on or off by epigenomes which in turn have been affected by environmental factors - a diathesis-stress.
One possible environmental factor is maltreatment in childhood.
Where did Caspi et al gather data from? What did they assess? What did they find?
Gathered data from the longitudinal Dunedin study that has followed about 1,000 people from where they babies in the 1970s.
Assessed antisocial behaviour at age 26.
Found that 12% of those men with the low MAOA gene had experienced maltreatment but were responsible for 44% of violent convictions.
What did Raine (2004) cite?
71 brain imaging studies showing that murderers, psychopaths and violent individuals have reduced functioning in the prefrontal cortex.
Prefrontal cortex = regulating emotion, controlling behaviour and moral behaviour.
Lowered activity in the prefrontal cortex = impulsiveness and loss of control.
What did Seo et al suggest?
Low levels of serotonin may predispose individuals to impulsive aggression and criminal behaviour, partly because serotonin inhibits the prefrontal cortex.
Dopamine hyperactivity may enhance this effect.
Alongside twin studies, where else can we identify evidence for inheritance in offending behaviour?
Adoption studies.
What did Mednick et al study? What did they find?
14,000 adoptees.
Found that 15% of sons adopted to a criminal family went on to be criminals compared with 20% whose biological parents were criminal.
What did Crowe find?
Adopted children who had a biological parent with a criminal record had a 38% greater risk of having a criminal record by the age of 18.
Adopted children whose mother didn’t have a criminal record only had a 6% risk.
Does the genetic research on criminal behaviour explain non-violent crimes.
No. Most of the genetic research on criminal behaviour relates to the association between criminal and violent or aggressive behaviour.
Criminal behaviour includes theft, fraud etc.
These are all non-violent.
What did Findlay (2011) suggest?
Suggests that crime is not a “natural” category - it doesn’t exist apart from how we choose to define it.
It’s a social construction. People have created the category of criminal behaviour and it includes many different types of crime.
In order for genes to cause criminal behaviour, they must be linked to a physical or psychological effect. What is one possible physical difference?
Head injury.
What did Harmon identify? What does this suggest?
Criminals report having had some head injury.
In general 8.5% of the US population have had a brain injury compared with 60% in US prisons.
This suggests that brain differences may be due to nurture rather than nature.
