Unit 2.2.1.2.1 - XYY Theory

• XYY theory suggests that crime could be attributed to chromosomal abnormality
• Chromosomes are structures in cell nuclei
• Humans usually have 46 chromosomes
• 44 chromosomes determine the shape and constitution of a body
• 2 chromosomes determine the gender of a person
• XX chromosomes determine the gender to be female
• XY chromosomes determine the gender to be male
• Chromosome abnormalities are possible within humans
• An example of chromosome abnormality is the XYY theory that counts an extra Y chromosome in a male
• Carriers fo XYY chromosomes can sometimes be called 'super males'
• Super males are suggested to be more aggressive and violent due to their extra Y chromosome
• Jacob's et al. (1965): XYY is over-represented in the prison population
• There are 15 in 1,000 super males within a prison population
• There are 1 in 1,000 super males within the general population
• John Wayne-Gacy: Said to have XYY syndrome. Sexually assaulted, tortured, and killed at least 33 men.