L3. Biological Explanations : Genetic & Neural

Genetic explanation

Suggests offenders commit crime because they inherit a gene, or combination of genes, that predispose them to commit crime.

Family Studies

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

Twin Studies

Christiansen (1977): 3500 twin pairs in Denmark, concordance rates:

35% for MZ males

13% for DZ males

Candidate Genes

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)

Neural Explanation

Suggests offenders commit crime because they have dysfunctions in their brain and nervous system that predispose them to commit crime.

Seretonin

Low levels of serotonin in prefrontal cortex linked to aggression

Serotonin inhibits the firing of the amygdala to regulate emotional responses (i.e. to anger)... low serotonin = more reactive amygdala

Prefrontal Cortex

Raine et al. (2000) found 11% reduction in grey matter volume of PFC in pps with anti-social personality disorder (ASPD)

Strength #1

P- Strength = research support

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

E- No convictions in bio + adoptee parents: 13.5% convictions. Convictions in bio parents only: 20%. Convictions in bio + adoptee parents: 24.5%.

L- So, genetic inheritance plays some role, but environment is also important (diathesis-stress).

Strength #2

P- Strength = research support

E- Cases et al. (1995): studied mice with deletion of MAOA gene on X chromosome

E- MAOA deficient males showed increased aggressive behaviour

L- So, animal study evidence for MAOA deficiency and aggression

Limitation #1

P- Limitation = cause-and-effect

E- Farrington et al. (2006): childhood risk factors (e.g. physical neglect) can cause neural differences

E- Rauch et al. (2006): trauma linked to both reduced frontal lobe activity and criminality

L- So, there may be intervening variables between neural differences and offending

Limitation #2

P- Limitation = biological determinism

E- At odds with criminal justice system - suggests that crime is not an act of free will

E- Implies criminals can never be fully rehabilitated - cognitive therapy ineffective

L- So, bio explanations have serious real-world implications