Atypical sex chromosome patterns

Klinefelter’s syndrome:

• (XXY) 1 in every 600 males

• Psychological characteristics = low language skills, reading ability, and problem solving

• Physical characteristics = gynaecomastia (breast development), underdeveloped genitals and reduced body hair

Turner’s syndrome:

• (XO) 1 in 5000 females chance

• Psychological characteristics = high reading ability, low maths skills, and spatial ability

• Physical characteristics = infertility, broad chest and waist/hips similar size

Contributes to nature-nurture debate

By comparing with chromosome-typical people you can see the differences. E.g. Turner’s has a higher verbal ability than ‘typical’ girls, so there is biological basis behind behaviour

Real-world application

Herliyh (2011), Australian study, 87 pps with Klinefelter’s. Found those treated when young had more benefits then those treated when they were older.

Sampling issues

In general, only extreme cases are examined. Boada (2009) found prospective studies following Klinefelter’s produce a more accurate picture as most people don’t experience many issues and lead highly academic lives.