XXY theory - genetic

• This theory of criminality suggests that some crime might be attributable to a chromosomal abnormality
• each individual has 23 pairs of chromosomes that determine aspects of their appearance , health and behaviour.
• biological sex is determined by sex chromosomes - either representing as XY for male and XX for female.
• XYY men , sometimes called super males. Have suggested that that extra Y chromosome makes them more aggressive and more inclined to be violent than males with a single Y chromosome.
• Jacob et al. (1965) - suggested that men with the XYY syndrome were more aggressive than normal ’XY’ men. There are also some studies that suggest XYY man are over-represented in the prison population.
• There are 15 sufferers per 1,000 in prisons and one per 1,000 in the general population.