'L3. Genetic and Neural Explanations'

Genetic explanation

Suggests offenders commit

crime because they inherit a

gene, or combination of

genes, that predispose them

to commit crime.

Crowe (1972): adopted children

- Biological mother with criminal

record: 50% risk for child to have

criminal record by age 18

- Biological mother with no criminal

record: 5% risk for child to have

criminal record by age 18

Christiansen (1977): 3500 twin pairs

in Denmark, concordance rates:

- 35% for MZ males

- 13% for DZ males

Tiihonen et al. (2015)

: 5-10%

of all severe violent crime in

Finland linked to MAOA and

CDH13 genes

MAOA

regulated serotonin, low activity variant is linked to

aggression

CDH13

regulated cell growth, linked to impulse control

(ADHD, substance abuse)

Raine et al. (2000)

found

11% reduction in grey

matter volume of PFC in pps

with anti-social personality

disorder (ASPD)

P1

Strength = research support

E1.1

Mednick et al. (1984): 13,000 Danish

adoptees

E1.2

1. 2. E

3. No convictions in bio + adoptee

parents: 13.5% convictions

Convictions in bio parents only:

20%

Convictions in bio + adoptee

parents: 24.5%

L1

So, genetic inheritance plays some role

– environment also important

(diathesis-stress)

P1

Strength = research support

E2.1

Cases et al. (1995): studied mice with

deletion of MAOA gene on X

chromosome

E2.2

MAOA deficient males showed increased

aggressive behaviour

L2

So, animal study evidence for MAOA

deficiency and aggression

P3

Limitation = cause-and-effect

E3.1

Farrington et al. (2006): childhood

risk factors (e.g. physical neglect)

can cause neural differences

E3.2

Rauch et al. (2006): trauma linked

E

to both reduced frontal lobe activity

and criminality

L3

So, there may be intervening

variables between neural

differences and offending