Jacob et al - XYY

• Weaknesses - Does Not prove it is the cause of violence
• Weakness: XYY men fit the stereotype of a violent offender so they are most likely to be convicted for a crime
• Weakness: The syndrome is rare
• Weakness: there is over representation in prisons due to low intelligence so they are more likely to be caught
• Strengths - Jacob et al found an association between XYY and offenders in prison for violent behaviour
• Strength: Price + Whitmore found some links between the syndrome and property crime
• Theory summary: some men have an extra Y chromosome leading them to be more violent