AC3.2 - Evaluate the effectiveness of biological theories of criminality

The strengths of Twin Studies?

-MZ twins are identical so criminal behaviour being identical is logical

-Ishikawa and Raine found a higher crime concordance rate in MZ than DZ twins

The weaknesses of Twin studies?

-If genes were only cause of crime then MZ twins would have 100% concordance rate

-Impossible to isolate and measure the effects of genes separately from environmental factors

The strengths of Adoption studies?

-Able to separate the issue from the environment

-Previous research found that adoptees were more likely to have criminal records if biological parents also had criminal records

The weaknesses of Adoptions studies?

-Gottfredson and Hirschi argue that adoption studies show that genes have little effect on criminality

-Many children are not adopted from birth and so environmental factors with biological parents may play a role

The strengths of Jacob’s XYY theory?

-Links have been found between the syndrome and property crime

-Relationship was found between XYY syndrome and offenders imprisoned for violent behaviour

The weaknesses of Jacob’s XYY theory?

-Syndrome is very rare and so cannot explain most crimes

-XYY men have lower intelligence and so are more likely to get caught, so over representation in prison

The strengths of atavistic theory?

-Lombroso was first person to study using objective measures

-Challenged idea that criminals are evil or choose to be criminal

-Examined medical records and patters instead of just individual criminal acts

The weaknesses of atavistic theory?

-Research has since failed to show a link between facial features and criminality

-Not everyone with atavistic features is a criminal and not all criminals have them

The strengths of somatotypes theory?

-Most serious offenders in Sheldon’s sample were ones with extreme mesomorphic body types

The weaknesses of somatotype theory?

-Criminality can be influenced by social class more than body type

-Doesn’t account for ectomorphs or endomorphs who commit crimes

-Appearance can be easily changed

The strengths of brain injuries/ disorders theories?

-Some correlation between EEG readings and psychopathic criminality

-Few extreme cases brain injury has led to significant changes in in personality and behaviour

The weaknesses of brain injuries/ disorders theories?

-Crimes caused by brain injury are rare, cannot explain all cases

-Prisoners higher likelihood of brain damage could be result of criminality (eg. Fighting)

The strengths of neurochemical theories?

-Testosterone levels and male offending both peak at same age, suggests link between the two

-Legal system recognises biochemical factors as partial defence

The weaknesses of neurochemical theories?

-Individuals may have biochemical predisposition but need an environmental trigger to cause actual offending

-Research shows that high testosterone levels led to verbal not physical aggression