The woman said he had a friend who used to come around and help her brother work on his cars.
She said that friend told his brother that sex was "pretty good", which was why her sibling wanted to experience it.
Her brother was 15 years old and she was two years younger when the alleged rape took place.
When she was in her late 20s, the complainant said he visited her with a big bouquet of flowers and apologised for his actions.
She asked him why he raped her and he just apologised and tried to make amends as best he could, she told the jury.
She told him: "That's okay, I forgave you years ago."
But it didn't alter the fact that she was raped, she said.
Defence lawyer Wayne McKean said his client's argument was that the sex with his sister took place in his room and that she pulled down her clothing rather than him removing the clothes.
She said it was not true.
She accused her brother of being a liar and of treating her like absolute dirt.
Earlier, Crown solicitor Mike Smith told the jury in his opening address that under the law, it didn't matter how long ago the alleged incident happened.
She went to police in 2002 and made a statement and in October 2010, her interview with police was recorded on video.
The man was spoken to by police on November 28, 2011, and he declined to comment or to make a statement.
The trial continues today.
