Ms Justice Murphy said that by not showing any remorse or responsibility for his actions, he had refused the most significant mitigation in a sentence for s3xual crimes.
The jury were unanimous in the 23 guilty verdicts against John Paul Hegarty, who now begins an eight-year sentence, with one suspended.
The 41-year-old denied r*ping his younger sister over the three-year period but the jury did not believe him, with deliberations finding John Paul Hegarty guilty on 23 counts.
Nora was aged between 9 and 12 at the time of the sexual crimes against her, with her brother aged 15 to 18.
She thanked her mother for supporting her and hoped that nothing in the trial would damage the relationship between the two of them.
Ms Justice Murphy said: “Her mother found herself in the awful position of having to give evidence in a trial where her daughter was the victim and her son was the perpetrator”.
Ending her victim impact statement, Nora Hegarty thanked friends, family, police and her legal team along with Support After Crime for their help.
She added: “I would not have done it without any of you. You believed in me and helped me carry on. Thank you from the bottom of my heart.”