XYY syndrome

• information about XYY syndrome?

  • 1 in 1,000 occurs due to genetic mutation.
  • following characteristics: taller than siblings, sever acne, lower intelligence, delay in speech, emotional difficulties, physically active.
• early studies on XYY syndrome?

  • Jacobs (1965), over representation of XYY in prison, 15 in 1,000
  • 1968, Daniel Hugon murdered a prostitute and it was found he had XYY syndrome.
• Theilgaard (1984)?

  took blood samples of 30,000 males born in 1940s. those with XYY syndrome have slightly lower intelligence and was more aggressive. suggested evidence for criminal gene if agg is a sign of criminality, but no conclusive evidence for a criminal gene since not all criminal acts are agg
• Re and Brikoff (2015)?

  review study, from past 50 years relating to XYY and crime. concluded there's no statistical evidence that an XYY man is predisposed to aggressive and deviant behaviour just because of his genotype.

  • XYY theory isn't credible explanation
• Witkin (1976)?

  carried out study in Denmark on 4,591 men. found that difference between XYY and XY wasn't significantly different when background variable were controlled for
• strength of XYY syndrome?

  • early research shows a link between XYY and antisocial behaviour. physical development, behavioural and emotional issues can be adressed early if looked into at an early stage in life
• weaknesses of XYY syndrome?

  • genetic research = practical difficulties
  • reductionist, ignores environmental aspects and only explains crime through a genetic mutation. Witkin (1976), XYY may be labelled due to physical characteristics which can influence antisocial behaviour.
  • women also carry out crimes, and won't have the XYY syndrome so it cannot explain all cases of crime
  • more recent research shows a link between XYY and crime isn't shown (Theilgaard, Re and Birkoff)