According to court records, the girl told personnel at her school about contact between her and her half brother.
A social worker from Washington County Department of Social Services was called and an interview was arranged.
The girl told the social worker her half-brother came into her room on two different nights and got into her bed, put his arm around her, kissed her and touched her leg, court records said.
When investigators approached the man at the home, he was asked what his relationship was with his half sister.
The man told police he kissed her, hugged her when she had no clothes on, and touched her genital area, court records said.
When asked if that was all that happened, the man then told investigators he had sexual intercourse with the girl on two occasions and that he thought it was consensual, according to court records.
Investigators again interviewed the girl, who then admitted her half brother had sexual intercourse with her twice, court records said.
But the girl told police she told him to leave her alone the first night and he didn't. The second night, she said she woke up and found him on top of her, court records said.
"I just want him to get help," the victim told Judge John H. McDowell Thursday.
The defendant said he was sorry.
After reading reports in the court files, McDowell said there was evidence of abuse within the family.
"I see the cycle of abuse here - the abused becomes the abuser," McDowell said.
Originally McDowell imposed a 12-year sentence, suspending all but the 4 1/2 years. The defendant was given credit for 314 days served in jail.