Atypical Sex Chromosomes

• Atypical Sex Chromosome Patterns

  Any sex chromosome pattern that deviates from the standard XX/XY formation; associated with distinct pattern of physical and psychological patterns
• Klinefelter's Syndrome

  Affects males, additional X chromosome (XXY), 1 in 500-750
• Klinefelter's Physical

  • Reduced body hair, gynecomastia (breast development), round body contour, long limbs, underdeveloped genitals, coordination issues, clumsiness, susceptible to female health issues eg breast cancer
• Klinefelter's Psychological

  • Poor language and problem-solving skills, passive and shy, lack sexual interest, poor response to stress, problems with memory
• Turner's Syndrome


  Affects females, absent X chromosome (X_), 1 in 1000-5000, have 45 chromosomes
• Turner's Physical

  • Amenorrhoea (no menstrual cycle), sterile – failed development of ovaries, broad 'shield' chest, low set ears, 'webbed' neck, hips not much bigger than waist, appearance of pre-pubescent girl
• Turner's Psychological


  • Higher reading ability, lower spatial and visual memory, lower mathematical ability, immature, trouble 'fitting in'
• Support - 'nature'

  Turner's = Higher verbal ability, more talkative than chromosome-typical girls - possible to see psychological and behavioural differences between chromosome-typical and atypical therefore shows nature has more effect because there's biological basis for difference therefore is cause of abnormal chromosomal structure
• Limitation - 'nurture' than nature

  Turner's = 'Socially immature' due to being treated as such for looking pre-pubescent thus indirect performance impact - difference in behaviour of Klinefelter and Turner syndrome patient is due to social influences, shows wrong to assume observed difference is due to nature therefore overexaggerates nature's influence and undermines social influences
• Support - practical application

  Herlihy 2011 = 87 w/ Klinefelter's identified and treated from young had more benefits than those diagnosed at adulthood - research likely to lead to earlier and more accurate diagnoses thus positive outcomes therefore increased awareness has space in real world
• Limitation - unrepresentative sample

  Only 1/3 of Klinefelter's population are aware they have the condition - this limits the extent to which generalisations can be made because less than 1/3 would've been the subject in the psychological research; conclusions are being drawn from a very small sample. Also when compared with the wider population, those with atypical chromosomes would appear differently, thus more likely to be treated differently from their peers which can complicate the extent of natural and nurture influences therefore low generalisability