The 69-year-old, who cannot be legally identified, was sentenced in Launceston Supreme Court on Thursday. 

The man was 18 years old when he began abusing his then seven-year-old sister.

Over a period of about seven years from the late 1960s the man raped her, forced oral sex on her and masturbated over her.

The abuse occurred at a number of locations across Tasmania and on a number of separate occasions. 

Shortly after turning 15, she became pregnant with her brother’s child. The baby boy was later adopted out. 

On Thursday the brother was convicted of maintaining a sexual relationship with a young person.

He was sentenced to 12 years in jail, eligible for parole after half. 

In handing his comments of passing sentence, Justice Robert Pearce said the abuse was an appalling breach of trust. 

“He initiated the sexual conduct, taking advantage of the power and authority he was able to exercise over her, arising from their relationships and respective ages,” he said. 

“His conduct has affected the complainant for most of her life and will likely continue to do so.”

Justice Pearce said the man must have been aware his acts were a grave criminal wrong. 

Speaking after the sentencing, the sister, now aged 57, said she was releaved that justice had been served. 

“It has taken me four years to get to this point and I have fought for justice on my own, only with the support of close friends,” she said. 

“I am very happy with the results of this sentencing. I feel like I am at a place where I can finally move on and leave that little girl behind.”