Biological explanations: Genetic and neural

Question 1

GENETIC >Twin studies: Christiansen

Answer 1

• Christiansen studied over 3500 twins in Denmark
• Concordance rates of 35% for MZ and 13% for DZ twins
• Not 100%, meaning other factors may play a role

Question 2

GENETIC > Adoption studies: Crowe

Answer 2

• Found adopted children whose biological mother had a criminal record had a 50% risk of having a criminal record by the age of 18
• Adopted children whose biological mother did’t have a criminal record only had a 5% risk

Question 3

GENETIC > Candidate genes

Answer 3

• Tiihonen conducted a genetic analysis of over 800 Finnish offenders
• MAOA gene regulates serotonin in the brain, linked to aggressive behaviour
• CDH13 linked to substance abuse and ADHD

Question 4

GENETIC > Diathesis stress model

Answer 4

• Role of genetics likely to be moderated by environment, genes are not acting alone
• Mednick took 13000 Danish adoptees, found genetic inheritance was important but environmental influence affects the likelihood of offending

Question 5

NEURAL > Prefrontal cortex

Answer 5

• Raine found 11% reduction in prefrontal grey matter in men with psychopathy when compared to a control group
• Suggests APD caused by reduced activity in prefrontal cortex

Question 6

NEURAL > Mirror neuron

Answer 6

• Mirror neuron fires both when the person acts and the same action is observed
• Suggests offenders may be able to feel empathy sporadically but not automatically
• Keysers > offenders watched a video of someone experiencing pain but only had an empathy reaction when asked to empathize with the person in the video
• Suggests offenders have a neural switch that requires conscious turning on and off

Question 7

Genetic strength: support for diathesis-stress

Answer 7

• Mednick > Study of 13000 Danish adoptees
• When neither biological nor adoptive parents had convictions, percentage of adoptees that did was 13.5%
• Figure rose to 20% when either had convictions and 24.5% when both had it
• Genetic and environmental influence plays a role in offending

Question 8

Genetic weakness: nature and nurture

Answer 8

• Many adoptions take place when children are older, so they spend years with biological parents
• Many adoptees are encouraged to maintain contact with the biological family, biological parents exert an environmental influence
• Do adoption studies separate nature and nurture?

Question 9

Neural strength: Brain evidence

Answer 9

• Kandel and Freed reviewed evidence of frontal lobe damage and anti-social behaviour
• People with such damage tended to show impulsive behaviour, emotional instability and inability to learn from mistakes
• Frontal lobe associated with planning behaviour
• Supports idea that brain damage may be a causal factor in offending behaviour

Question 10

Neural weakness: Intervening variables

Answer 10

• Other factors may contribute to antisocial personality disorder
• Farrington studied a group of men who scored high on psychopathy. They experienced various risk factors during childhood, such as being raised by a convicted parent, being physically neglected, etc
• These early childhood experiences may have caused APD and some of the neural differences associated with it
• Suggests that relationship between neural differences, APD and offending is complex