AN IPSWICH boy forced his seven-year-old sister to lick his penis if she wanted to watch television.
The teen also raped a five-year-old boy - causing injuries.
He also had touched his sister's genitals when she was aged five.
The accused boy, aged 13 to 15 at the time, was sentenced to three years detention and ordered to serve 50% when he pleaded guilty in Ipswich Children's Court in April.
On Tuesday, he lost a bid to reduce that sentence in the Queensland Court of Appeal.
A Griffith Youth Forensic Service report revealed the accused boy had suffered extreme bullying, disrupted schooling, social isolation, loss of home and family environment changes in his formative and early adolescent years.
"(The boy's) social isolation during an important stage of his adolescent development subsequently affected his understanding of healthy relationships and limited his exposure to positive modelling through peers," the report said.
"Further contributing to his offending was his relatively unsupervised access to the victims."
Justice Gotterson, in a judgment delivered on Tuesday, said he did not accept submissions that the head sentence was manifestly excessive.
"In my view, the learned judge had appropriate regard for the evidence before her with respect to the issue of re-offending and did not err," he said.
Justice Robertson Gotterson said the boy's lawyers had argued his actions could not compare to a case the sentencing judge had given weight to.
But he said this boy's actions had gone over several years with increasing gravity culminating in "a very damaging rape".
"His victims were much younger and more vulnerable," he said.
Two other Court of Appeal justices agreed.
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