Jacobs XYY Flashcards
What is Jacob’s XYY theory?
Men with an extra Y chromosome are more likely to commit crime
What is the XYY syndrome also known as?
Super male syndrome
How does XYY syndrome occur?
It is an error that occurs during fertilisation — it is not inherited
What are the characteristics of XYY males?
Increased levels of testosterone
Severe acne during adolescence
Often have learning disabilities/a lower IQ
Slightly taller than average
Sometimes have minor behavioural problems
What happened during Jacob’s XYY study in 1965?
Patricia Jacob’s examined 197 Scottish prisoners for chromosomal abnormalities using blood tests
Results suggested that men with XYY syndrome were more aggressive and potentially violent
How are XYY men over-represented in the prison population?
For every 1000 prisoners, 15 suffer from XYY syndrome
For every 1000 people in the general population, 1 suffers from XYY syndrome
Who was John Wayne Gacy?
An American serial killer and rapist
He sexually assaulted, tortured, and murdered al least 33 teenage boys and young men
It was believed he had XYY syndrome
What are the strengths of XYY theory?
Uses scientific methodology
Study could help with potential treatments — real life application
Other studies have supported his claims (increases reliability)
What are the weaknesses of XYY theory?
There is conflicting research (decreases reliability)
XYY males are rare so theory is hard to prove
Cannot establish cause and effect as subjects had other forms of medication
Relies heavily on genetics and ignores behaviourist approach
Not very representative
