Huh? Seems to me not testosterone, but hysterical parents are the problem here. Quote from the doctor: "He can get a girl pregnant. He will not hesitate if given the opportunity." WTF??? What a bunch of nonsense.
The doctor accurately describes what testosterone does to boys. Once a boy starts producing testosterone in large amounts he matures sexually, becomes capable of getting women pregnant, and develops a strong interest in doing so. The result is called puberty.
This is as true at 9 as it is at 16. It is much rarer for boys to start producing testosterone at 9, but if it happens, the results are perfectly predictable. (Ditto for girls. There is no known lower age limit at which the body responds to sex hormones. See http://en.wikipedia.org/wiki/Lina_Medina for an extreme example.)
This boy had higher than normal levels of testosterone, and was facing it with unusually little maturity due to his young age. Both factors bode poorly for self-control.
