It was 1963 when she was born; Mr Liston was 18 and Mrs Liston was 16.

The Canberra teenagers were given no choice but to give her up for adoption.

"At the time it was probably seen as a solution to the problem," Mr Liston said.

"There was no bonding, or touching, or holding or anything, I was not present [at the birth]."

They married four years later and went on to have two more daughters.

When the pair became empty nesters, Mr Liston couldn't get thoughts of his first daughter out of his mind.

They went through official channels and were finally able to get in touch with her several years ago.

"We had her 43rd birthday together and we haven't missed one since, she's 51 now."

Mrs Liston said she had few memories of the time of the adoption as she had pushed them out of her thoughts:

"I think that's probably why I survived without being too struck by grief.

"It's been wonderful that we found her and everything seems to be normal, except there's 43 years missing."

Their story doesn't stand alone.

The Narrabundah couple are among Australians whose stories of forced adoption are featured in a new exhibition at the National Archives.

Former Prime Minister Julia Gillard was in Canberra to open Without Consent: Australia's past adoption practices on Monday.

It was Ms Gillard who, in 2013, offered a national apology to the thousands whose lives were affected forever by forced adoption.

Ms Gillard recalled the privilege and solemn duty she felt on that day and said the exhibition would connect those who knew little about the adoptions with a hard, uncomfortable and emotional truth.

She paid tribute to the courage and generosity of spirit shown by families who had come together and given a public voice to their pain.

"Particularly when across their lifetime, so many were told to bury this secret, to never acknowledge it, never speak to anyone about it.

"Our nation would not have taken the step of delivering the apology without your courage and your preparedness to come forward and tell your stories."

Former Family Court judge Nahum Mushin used the exhibition opening to agitate for uniform laws for domestic adoption in Australia

National Archives director-general David Fricker said the touring exhibition would give an insight into a shameful, and previously hidden, period in the nation's past.

"We want this exhibition to open the hearts and minds of Australians to a different perspective on the experiences of adoption."

Curator Amy Lay was struck by the resilience, but also the optimism and hope, of the parents and children who shared their experiences.

"It's important to get past the idea that traumatic events or difficult history is about numbers and facts and statistics. This is about people."