Biological Theories - Genetic and Neural

Genetic explanations

Suggests that potential offenders can inherit a set of genes that would predispose them to commit crime.

Strength of twin studies

Can measure concordance rates and investigate nature vs nurture - particularly in MZ twins that have been raised apart

Disadvantage of twin studies

Can’t generalize findings as twins are bought up in the same house.

Lange (30) study

Studied 13 MZ twins and 17 DZ twins, where one of each twin had spent time in prison. 10 of the MZ twins but only 2 of the DZ had co-twins who had spent time in prison - suggesting a genetic link.

Christiansen (77) -

Studied over 3500 twins pairs in Denmark. Found a concordance rate of 35% for MZs and only 13% for DZs for offender behavior. Supports the view that offending may have a genetic component.

Who researched candidate genes

Tiihonen et al (2014)

Tiihonen et al findings

Revealed to abnormalities that may be associated with violent crime. The MAOA and CDH13 gene combination make individuals 13x more likely to have violent behavior.

Tiihonen et al study

Genetic analysis of 900 Finnish offenders

MAOA gene role

Regulates serotonin in the brain

CDH13 role

Linked to substance abuse and attention deficit hyperactivity disorder (ADHD).

Diathesis stress model

Criminal behavior is a result of genetic predisposition and a psychological trigger e.g. raised in a dysfunctional environment. Offending is not just a result of certain genes.

Caspi et al (2002)

Followed 1000 ppts from babies and assessed their anti-social behavior when they were 26. Found that 12% of the men with MAOA genes had experienced mal-treatment when they were younger and were responsible for 44% of the violent crimes recorded.

Neural explanation

Evidence to suggest there may be neural differences in the brains of offenders and non-offenders.

Anti-social personality disorder (APD)

Also known as psychopathy, where a person has reduced emotional responses and a clear lack of empathy for the feelings of others.

Prefrontal cortex role

Regulates emotional behavior

Prefrontal cortex and APD

People with APD show reduced activity in the prefrontal cortex as demonstrated by Raine.

Raine (2000) study

Found an 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD then control groups.

Keysers research (2011)

Found that offenders with APD can empathize, but not naturally. When asked to empathize (with person on film in pain) then they were able to by activating mirror neurons in their brains.

Keysers research conclusions

Criminals with APD may have switches in their brains that turn on empathy, whereas most people have it on all the time.

AO3 - twin study issues

Early twin studies often poorly controlled and unreliable as MZ and DZ twins were based on appearance rather then DNA testing. Also usually small samples and unusual in the fact they were twins, therefore problematic in generalization. Usually raised in same environment, creating confounding variables in concordance rates.

AO3 - biological reductionism

Criminality is complex and environmental factors must be considered. Katz et al (07) points out that crime runs in families, but as does emotional instability, mental illness and poverty. It’s therefore to disentangle genetic and neural influences from other possible factors.