A teenager who started sexually abusing his little sisters when the youngest was four used their deceased father's greenhouse to commit the crimes.
In a decision published on Thursday, August 6, the ACT Supreme Court handed the man, now 30, an eight-year jail sentence to be suspended after four years and six months.
The abuser, who cannot be named due to his age at the time, previously pleaded guilty to numerous historical charges including incest and committing acts of indecency on a child.
The brother was 14 when he first started sexually abusing his four-year-old sister. This continued for years until he was 23.
He was 17 when he started sexually assaulting his other sister, who was 13 or 14 at the time.
The teenager persisted in his actions despite both sisters physically resisting, including kicking him in the genital area.
Justice Belinda Baker found the offender knew his actions were wrong and "his moral culpability for the offending increased with each passing year".
"Each of the offences occurred at the family home where the victims were entitled to feel safe, loved and protected," the judge said.
"[The crimes] involved the betrayal of a family relationship by an older brother against his younger sisters."
The brother often sexually abused his younger sister in their deceased father's greenhouse. This continued for years with him telling the girl to keep the crimes "a secret".
The location held sentimental memories for the girl who missed her father. The abuser knew his other family members were unlikely to enter the greenhouse because the memories were too difficult.
On one occasion, the brother cornered his younger sister and used force to sexually abuse the girl who was resisting.
In April, the older victim said in an impact statement that "when somebody makes a mistake like this they deserve to be put to death".
The younger sister referred to her brother as "the entity" and said she did not realise what was happening to her until she started sex education in school.
Once she was aware, the victim said she started to fight back and came to school covered in bruises.
"The first person I trusted turned out to be the worst person to trust," she said.
"[Being sexually abused by a relative] makes you contemplate, do I destroy my family in seeking justice or do I destroy myself?"
Justice Baker accepted the abuser's exposure to incest pornography from age 13 "led to a normalisation of that type of sexual activity, distorting his understanding of sexual relationships".
However, she took into account that he persisted in the abuse despite knowing he was causing his sisters pain, and despite a warning from his older sister that "she would take action to ensure he was removed from the family home".
In a letter to the court, the now-30-year-old said he "cannot express how much guilt and self hatred [he has] for this catastrophic failing".
The judge found he was remorseful and had good prospects of rehabilitation and a willingness to engage in rehabilitation programs while in jail.
He will be released and placed on a good behaviour order in September 2029.
