The royal commission into child abuse on Friday heard from psychiatric nurse Michael Groome, who said it was widely known at Nunawading's Winlaton​ Youth Training Centre in 1979 that the young girl was suffering from incest.

The woman, who cannot be named, told the inquiry that her father raped her from the age of 13 and had four children to him. She feels betrayed by the system that allowed her father to continue abusing her for almost 30 years.

Dr Groome counselled her when she was a teenager at the correctional and training centre, and took detailed notes outlining his knowledge of the incestuous relationship.

Under intense questioning about why the abuse was not reported to police, and whether the case was treated differently because the offender was her father, Dr Groome acknowledged there had been a distinction drawn between private and public crime.

He said there had been a strong focus on working within the family unit, and that theory would sometimes override legal requirements such as reporting rape to police.

"Often in psychiatric services in those days there was attempt to work with families a lot," he said.

"There was a strong movement in the late 1960s and 1970s and into the 1980s, I suppose, where the emphasis was on family therapy."

Dr Groome, now a semi-retired psychologist, also told the commission he did not believe it was his responsibility to notify the police.

"She was a ward of the state ... the department was responsible for those decisions," he said.

"I would make recommendations about what should be done in terms of contact with the family and so on, but I don't think that overall it was my responsibility to report that to the police."

When asked if there was anything he wanted to say about his contribution to her care, Dr Groome expressed remorse for failing her.

"I do want to say that things seem to have been bungled and, probably, if we had intervened properly at the time she wouldn't have ended up having the life that she had up until recently, and I'm very sorry about that.

"I don't know how I can express that any stronger."

The woman has told the royal commission her two youngest sons still don't know their grandfather is also their father. He was eventually jailed in 2010 for a minimum of 18 years.

The royal commission's hearings in Melbourne are investigating the horrifying experiences of children in the Victorian government's Winlaton​, Turana and Baltara​ facilities from the 1960s to their closure in the 1990s. The inquiry continues.