biological explanation: genetic and neural

Question 1

Twin studies - Christiansen

Answer 1

Christansen (1977) studied 3500 Danish twins, found 35% concordance rate for offending in MZ males and 13% for DZ males. Indicates that there may be underlying predisposing traits

Question 2

Twin studies - Crowe

Answer 2

Crowe (1972) adopted children with an offender biological mother had a 50% risk of having a criminal record by 18. Those with a non-offending criminal mother had a risk of 5%

Question 3

MAOA

Answer 3

Regulates serotonin in the brain, linked to aggressive behaviour
5-10% of crime in Finland attributed to this

Question 4

CDH13

Answer 4

Linked to substance and ADHD
5-10% of crime in Finland attributed to this

Question 5

Diathesis-stress model

Answer 5

Even if there is a genetic predisposition it is moderated by the effects of the environment. A tendency towards offender behaviour may come about through combination of genetic predisposition and biological or psychological trigger e.g. having criminal role models

Question 6

Antisocial personality disorder

Answer 6

Reduced emotional response, and a lack of empathy for others, characterises many convicted offenders

Question 7

Prefrontal cortex

Answer 7

Raine, studied APD brain, conducted several brain-imaging studies. Found reduced activity in prefrontal cortex which regulates emotional behaviour. (2000) Found 11% reduction in grey matter volume in prefrontal cortex of APD brains compared to control

Question 8

Mirror neurons

Answer 8

Keysers (2011) offenders could empathise but had to be asked to when watching a person on film experiencing pain. When asked empathy reaction controlled by mirror neurons activated. APD individuals not without empathy but may have a neural switch unlike standard brain which is permanently on

Question 9

Twin evidence

Answer 9

Assumption of equal environments as they are brought up together. However ‘shared environment assumption’ applies more to MZ twins than DZ twins as MZ look identical so people (parents) treat them more similarly which affects their behaviour. High rates in MZ twins may be due to treatment not genetics

Question 10

Diathesis-stress model support

Answer 10

Mednick (1984) studied 13000 Danish adoptees, when neither bio or adoptive parents were offenders adoptee conviction rate was 13.5%. When biological had a conviction rates were 20%. When both biological and adoptive parents had a conviction rates were 24.5%
Shows both genetic inheritance and environmental influence play a role in offending

Question 11

Nature and nurture

Answer 11

Many adoptions take place when children are older so several years spent with biological parents, many adoptees maintain contact with the biological family so biological parents exert environmental influence. Adoption studies do not completely separate nature and nurture

Question 12

Brain evidence

Answer 12

Kandel and Freed (1989) reviewed evidence of frontal lobe damage (inc. PFC) and antisocial behaviour - people with damage showed impulsive behaviour, emotional instability and inability to learn from mistakes. FL associated with planning behaviour. Supports the idea that brain damage is causal factor in offending

Question 13

Intervening variables

Answer 13

Farrington (2006) Group of men who scored high on APD, had experienced risk factors during childhood e.g. physical neglect. Early childhood experience may have caused APD and neural difference such as reduced activity.
Relationship between neural differences, APD and offending is complex so other intervening variables may have an impact

Question 14

Biological determinism

Answer 14

Based o this behaviour is determined by out of control neural/genetic factors so a person shouldn’t be held responsible for a crime.
Justice system is based on notion we have responsibility for our actions except in extreme circumstances e.g. insanity. Identification of biological precursors complicates this principal