Her client had lived with inappropriate role models and inappropriate actions towards her by male members of her family.
Judge Stephen O'Driscoll said the male offender was being cared for by in a foster home when he and his foster mother began a sexual relationship. She was 30 and he was 13. Their daughter was born when he was 14.
He was told he was the father but because of his age at the time of the girl's birth, he had little contact with her until she was about 16.
The father made contact with his daughter in 2010. A visit was arranged and, after several more visits, the father moved into his daughter's family's home. Their sexual relationship began in August, 2010 and continued until May this year.
While the offending was outside society's norms, it was incest between consenting adults, Ms Farnham said.
Psychiatric and psychological reports indicated the pair had genetic sexual attraction, a phenomenon which sometimes occurred between family members reunited after a long separation.
She asked that her client be convicted and discharged. The doctor who had interviewed her said that would "help her to psychological normality".
Judge O'Driscoll said pre-sentence reports showed the daughter had a "difficult and chaotic background rife with sexual inappropriateness" and a degree of pity and compassion was required about her eventual relationship with her biological father.
Society might see imprisonment as a suitable deterrent penalty, Judge O'Driscoll said, but he believed a rehabilitative sentence was appropriate because of her age and because she had a child to care for.
He sentenced her to 12 months' supervision.
The man was sentenced to 300 hours' community work and 12 months' supervision.
Judge O'Driscoll said there could not be legislation against sexual attraction but he warned the pair it would be "highly likely" they would be sentenced to imprisonment if they appeared again on similar charges.
"This must stop. These sort of relationships do not last and are fraught with difficulties."
Both were granted final name suppression.