Another 47-chromosome occurrence is XYY Syndrome. In this syndrome, the hormonal and physical appearance of the individual are evidenced as a normal male, but behaviour is effected. Typically, XYY Syndrome people are bisexual or paraphilic (paedophilia, exhibitionism, voyeurism, etc.), and show very poor impulse control.
Where Klinefelder’s and XYY Syndrome are examples of an extra chromosome, Turner’s syndrome is a case of a missing sex chromosome. These individuals possess 45 chromosomes (written s XO), are unable to develop gonads, and are free of all sexual hormones, except that crossing over from the mother during fetal life.