Nanko S
Folia Psychiatr Neurol Jpn. 1979;33(1):29-34. doi: 10.1111/j.1440-1819.1979.tb00171.x.
The mental features of nine 47,XYY males and six 47,XXY males found among Japanese juvenile delinquents were examined. The results of intelligence tests suggested a slight impairment among 47,XYY and 47,XXY males. The psychiatric interviews and the psychological tests revealed that 47,XYY males had a high activity level while 47,XXY males had a low one. Analyses of the offense type and psychophysiological features supported these findings. As the activity level is considered to be largely determined genetically, the extra Y is suspected to be responsible for the high activity level and the extra X in males to be responsible for the low activity level.
