Forensics - biological explanation

Question 1

what are genetic explanations

Answer 1

• offenders inherit a gene that predispose them to commit a crime
• twin and adoption studies
• candidate genes
• diathesis-stress model

Question 2

what are twin and adoption studies

Answer 2

Christiansen
- studied 3500 twin pairs in Denmark
- concordance rate for offender behaviour of 35% for MZ and 13% DZ
- offender behaviour checked against police records

Crowe
- adopted children whose biological mother had a criminal record had a 50% risk of criminal record by the age of 18
- adopted children whose biological mothers didn’t have a criminal record had a 5% chance

Question 3

what are candidate genes

Answer 3

Tihonen et al
- genetic analysis of 800 Finnish offenders
- MAOA and CHD-13 gene involved with violent behaviour
- MAOA = regulates serotonin in the brain and is associated with aggressive behaviour - CHD-13 = substance abuse and ADHD
- 5-10% of all violent crimes in Finland was associated with these genes

Question 4

what is the diathesis-stress model

Answer 4

• genetic predisposition
• biological / psychological trigger

Question 5

what are the strengths of genetics

Answer 5

Mednick et al
- 13,000 Danish adoptees
- 13.5% = adoptive parents and biological parents no convictions
- 20% = only biological parents had convictions
- 24.5% = both biological and adoptive parents had convictions

Question 6

what is the limitation of genetics

Answer 6

• assumed twins also have the same environment
• apply more to MZ than DZ
• MZ twins are treated more similarly which affects behaviour

Question 7

what are neural explanations

Answer 7

• explanation of behaviour in terms of functions of the brain and nervous system
• activity of brain structures

Question 8

what is the evidence of the prefrontal cortex

Answer 8

Raine
- conducted study of the antisocial personality disorder (APD) brain
- individuals with APD have reduced activity in the prefrontal cortex
- prefrontal cortex regulates emotional behaviour
- 11% reduction in the volume of grey matter

Question 9

what is the evidence of mirror neurones

Answer 9

Keysers
- when offenders asked to empathise they could empathise
- APD individuals have a neural switch that can be turned on and off
- normal brain empathy is always present

Question 10

what is the strength of neural explanations

Answer 10

Kandel and Freed
- reviewed evidence of frontal lobe damage and APD
- people with damage tend to show impulsive behaviour, emotional instability and an inability to learn from their mistakes
- brain damage may be a casual factor in offending behaviour

Question 11

what is the limitation of neural explanations

Answer 11

Farrington et al
- studied a group of men who scored high on APD
- these individuals experienced various risk factors in childhood
- early childhood experiences may have caused offending behaviour