XYY theory

Cards (6)

  • XYY's theory- humans have 23 pairs of chromosomes, males have XY and women have XX.
  • An abnormality in the male chromosome creates an extra Y chromosome making XYY.
  • Criminals are believed to have the extra Y chromosome
  • Males with XYY syndrome have an increased risk of behavioural, social and emotional difficulties. This can include ADHD, more aggression and slower than average learning.
  • John Wayne Gacy is said to have XYY, he sexually assaulted, tortured and raped at least 33 men in America.
  • Patricia Jacobs took blood samples from 197 men in a maximum security prison in London. All participants had aggressive behaviour, 12 having chromosome abnormalities. The rate is prison (3.5%) was much higher than the general population (0.2%).