Sex offender treatment in demand for kids; stuff.co.nz, March 6, 2008 
A Christchurch agency that treats sexual offenders is now dealing with children as young as five. 
STOP Trust manager Don Mortensen said the age of pre-adolescents they were treating had got lower in the past few years, and they now were seeing some children in their first year of primary school.
"We're now working with children down to the age of five and six," he said.

Children who sexually abuse: what's the strategy? Simon Hackett, communitycare.co.uk, October 4, 2007 
About a quarter to a third of all cases of sexual abuse coming to the attention of professionals concern situations where children and young people are the alleged perpetrators of the abuse. 
Almost all reports on this topic state this same, well worn statistic, and I am sick of it. [...]
Many say they found the professional system overwhelming and bewildering, and incidences of poor communication on the part of professionals were commonplace.