BIOLOGICAL THEORIES OF CRIMINALITY : GENETICS Flashcards
What are the BIOLOGICAL theories of criminality (Genetic)
Genetic:
Jacobs - XYY
Twin and Adoption studies
Briefly outline Jacob’s XYY study as an explanation of criminality
The Y chromosome is the ‘male’ chromosome, and Jacob argued that the genetic abnormality of XYY on the 23rd chromosome means that some men are more prone to aggression and criminality than others.
Studies estimate that 1 in 1000 males have an extra Y chromosome and the theory argues that these individuals produce extra testosterone that can predispose them to criminality. Jacob called these individuals ‘Super Males’
One strength of Jacob’s XYY study into criminality: Supporting research
Research within the prison system supports the theory as studies suggest that there are 15 in 1000 prisoners with XYY, compared to just 1 in 1000 men in the general population.
15 in 1000 prisoners is a substantial figure that provides credibility for the XYY theory
One weakness of Jacob’s XYY study into criminality: Link between XYY and aggression
Subsequent research has found no link between the XYY genotype and aggression.
Theilgaard undertook research into men with the XYY genotype and found that XYY can cause an increase in height in individuals but not an increase in aggression.
This shows that findings concerning the link between XYY and aggression are not reliable.
One weakness of Jacob’s XYY study into criminality: IQ
The XYY genotype has been linked to lower IQ.
This is a limitation as critics of the XYY theory have argued that the higher prevalence of XYY in prison isn’t due to them being particularly criminal, but rather is because they are more likely to be caught. Research has found that XYY individuals are generally 10-15 IQ points lower than their siblings.
This shows that there are others factors which can explain the higher prison population rather than a particularly aggressive genotype.
Briefly outline twin and adoption studies as an explanation of criminality
Twin studies compare identical twins (MZ / Monozygotic) who share 100% of their genes to non-identical twins (DZ / Dizygotic) to see whether the twins share the same criminal characteristics. If they do, their is said to be a concordance rate.
Adoption studies investigate whether there is criminality in the biological or the adopted parents of the ‘criminal’ individual. If there is a prevalence of criminality in the biological parents rather than the adopted parents, it is seen as evidence to support the idea that criminality is biologically determined through inherited genes (i.e. nature) rather than the individual’s upbringing (i.e. nurture).
One strength of twin and adoption studies as an explanation of criminality: Supporting research
Rhee and Waldman conducted a meta-analysis of 51 twin and adoption studies and found that aggressive and anti-social behaviour was largely due to genetic contributions.
This shows that there is a wide range of research indicating that there is a biological genetic basis to criminal behaviour.
One strength of twin and adoption studies as an explanation of criminality: Policy development in countries around the world
Although highly controversial, policy development across several countries in the world have been impacted.
This development is linked to the idea that criminality is transmitted via a ‘criminal gene’.
Capital punishment is strongly rooted in biologically deterministic views that criminals are unable to change their inherited behaviour.
Although abolished in the UK in 1969, capital punishment policies still remain in many countries and maintain the death penalty to this day (e.g. several US states)
One weakness of twin and adoption studies as an explanation of criminality: Failure to identify a ‘criminal’ gene
Scientists have failed to identify a single ‘gene’ that is responsible for criminality.
Gene mapping is the biological attempt to pinpoint certain genes to causing behaviours.
This shows that the failure to identify ‘criminal’ genes means we must acknowledge that at the very least it is the interaction between genes with the environment which is the cause of criminal behaviour (i.e. It is factors of nurture as well as nature)
