Genetic and neural explanations Flashcards
What does the genetic explanation suggest?
That there is one or a combination of genes which predispose an individual to commit a crime
What did Lange (1930) find?
Twin study
13 Monozygotic twins and 17 dizygotic twins with one twin in each having served time in prison
Found that 10 monozygotic and 2 dizygotic twins had the other twin in prison
What did Christiansen (1977) find?
Studied 87 MZ and 147 DZ have found concordance rates of 33% for MZ and 12% for DZ which supports the view that offending may have a genetic component
What are limitations of twin studies?
There are never 100% concordance rates which leaves room for environmental factors to influence.
Twins tend to share the same environment growing up
Twins are unusual samples - hard to generalise
What are candidate genes?
a gene which is thought to be responsible for a particular trait or behaviour
What did Tiihonen et al (2014) find?
Analysed 900 offenders and revealed abnormalities on two genes that may be associated with violent crime.
MAOA gene - controls serotonin and dopamine levels and is linked to aggressive behaviour
CDH13 - linked to substance abuse and ADD
Individuals with the high risk combination were 13 times more likely to have a history of violent behaviour
What is the issue with Tiihonen’s research?
It is new and therefore yet to be replicated
What is the diathesis-stress model?
A tendency towards criminal behaviour may come about through a combination of genetic predisposition and a biological psychological trigger
What does the neural explanation suggest?
APD is associated with reduced emotional responses, a lack of empathy for the feelings of others.
Condition which categorises many criminals
What did Raine report?
Reported that many APD studies showed that individuals with anti-social personalities have reduced activity in the prefrontal cortex which is the part which regulates emotional behaviour
What did Raine et al (2000) find?
An 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls
What did Keyers et al (2011) find?
When criminals were asked to empathise, their empathy reaction activated which was controlled by mirror neurones
This shows that criminals do have empathy but they are able to turn it off using a neural switch unlike normal brains which can’t
What did Medenick et al (1984) find?
support for diathesis stress model
13,000 Danish adoptees
13.5% of adoptees had a criminal conviction when neither an adoptee or biological parent had convictions
20% when either of the biological parents had convictions
24.5% when both adoptive and biological parents had convictions
Low concordance rates mean the environment cant be ruled out
What are the problems with adoption studies?
Much of a childhood is spent with biological parents
Many adoptees still see their parents regularly
Difficult to assess the environmental impact
What is the biological reductionism debate?
Reducing offending behaviour to neural or genetic influences is too simplistic
Crime runs in families but so do mental health problems
Concordance rates are never 100%
