It was late at night in 2008 when Shauna Bostock’s phone rang. It was Uncle Gerry, from Sydney, sounding “strangely incredulous”. He couldn’t quite believe the news he had just heard. “Guess who our white ancestors were?” He paused for dramatic effect. “They were slave traders. Imagine that!” Snorting with laughter, he added: “Those white ancestors of ours must be rolling in their graves knowing we turned out to be a mob of blackfellas.”

Until then, the Bundjalung woman had only known of Augustus John Bostock, “the whitefella who gave us our family name”. Uncle Gerry’s news ignited in her “a burning desire to know more”. But it also left her feeling numb. Bostock realised she “simply didn’t have the words to describe how I felt”. Now, in her book piecing together her family history, Reaching Through Time, she has found those words.

But finding out about her slave trader ancestors from the mid-1700s turned out to be easier than accessing the records for her ancestors who had lived under the Aborigines Protection Board in the early part of last century.

Her white ancestor, she would soon find out, was not only a slave trader but a convict – one of two slave traders sent to Australia for the crime. His life had already been documented by an avid amateur genealogist and a professional historian. In the mid-1700s, Capt Robert Bostock transported African captives in terrible conditions and sold them in ports across the world. His son Robert had followed his footsteps at a time when slavery was being abolished and criminalised. Robert Bostock Jr would be found guilty under the Slave Trade Felony Act and transported to Australia in 1815 for a term of 14 years. In the colony he would be pardoned and become wealthy and respectable.

His grandson Augustus John Bostock would travel north from Sydney and at the age of 27 marry One My, AKA Clara Wolumbin, of the Wollumbin people – Bostock’s great-great-grandmother. Finding One My was a big moment for Bostock; she actually had a name for one of her Aboriginal ancestors. “Now I had a starting point.”

‘I felt it was my calling’

As she turns off the M1 and sees the great heft of Wollumbin Mt Warning, Bostock breathes in, exhales and feels a sense of peace. Rising spectrally above the towns and villages of the New South Wales northern rivers, the sacred mountain and its powerful presence dominate the landscape. For Bostock, this is her ancestral home.

She felt her ancestors close by as she researched her book. “As soon as I started doing my family history, the heavens opened up.”

Erased from history, dispossessed, forgotten – her ancestors came alive in the archives as if they had been waiting for someone to find them there, to tell their stories. They came rushing down the generations. “When you go to the archives, sometimes they are bound together and tied up with cotton tape. And by releasing them from their binding, reaching in and pulling my ancestors out, it is like reaching through time to bring them in front of you.”

Bostock thinks back to being a mature-age student studying to be a primary school teacher in 2003. After a tough lecture on Aboriginal segregation and the indenture of teenagers, she was struck by the realisation that few Australians know the true history of Aboriginal people in this country. “What do you know about missions and reserves?” she asks. “Nothing. What you do know about the history of Aboriginal people are cherrypicked: Mabo and stolen generation. I am not discrediting these milestones, but they’re isolated little milestones on the timeline of history.”

She began with the goal of tracing her four Aboriginal grandparents’ family lines as far back as she could in Australia’s written historical record. “I felt it was my calling,” she says. It was a way of addressing unfinished business, and building a “bridge between my ancestors who witnessed colonisation – and my life today as an urban Aboriginal woman”.

The records locked away

The multigenerational story of her family is the story of the modern history of this country.

“I have always joked,” she writes, “that my family members are the ‘Forrest Gumps’ of blackfellas.” They were there at the frontline of all of it.

But the individual stories of her people are not known publicly because all the records of their lives under the Aborigines Protection Board are locked up in the Aboriginal affairs department, off limits to the general public. “And none of them see the light of day.” Bostock was only able to access them because she could prove that she is a direct descendant of the people whose files she was requesting. Other historians cannot get access; their truth remains hidden.

Her own family’s truth was illuminating. In the files were “copious records”. The Aborigines Protection Board, which operated for more than six decades before ending in 1969, controlled every aspect of the lives of Aboriginal people in northern NSW. It forced them to live on ever-shrinking reserves, sometimes starving them out to force them to move from one reserve to another. “People were just shuffled and shuffled and shuffled,” Bostock says. It removed children from their families – the girls sent to Cootamundra Domestic Training Home to be trained as unpaid domestics; the boys to Kinchela Boys Home to be trained as farm labourers. “They didn’t see them as human beings,” Bostock says.

And there were many stories of resistance. Her great-grandmother Nellie Solomon, apprenticed to Mrs JC Edwards of Kyogle, had stood her ground and refused to go when white authorities, possibly with a police officer, had come to take her to Sydney. She was 14 years old. Bostock had found her in the archives in the last minutes before she was due to leave to catch a flight from Sydney to her home in Brisbane. “Yes Nellie!” she shouted in the silence of the reading room, slamming her hand on the table top.

But while the search for information about Nellie elicited exhilaration, “there have been countless times when I have found the records so saddening, so shocking, and at times so infuriating, that they have caused streams of tears to pour down my cheeks”, she writes.

Bostock set out to “restore the humanity” of her ancestors. And she has.

“There is this burden that builds and builds and it is sort of like you’re holding all this sadness, but the wonderful thing that helps you put down this burden are shining moments of humanity and kindness,” she says now. The process of truth telling creates healing. The ancestors are remembered, acknowledged, no longer erased and unknown; the spiritual connection is restored.

‘It was like a washing away of grief’

Towards the end of writing the book, Bostock contacted the grandson of JP Howard, who had managed the lives of her ancestors at the Kyogle Aborigines Reserve. Alan and Carolyn Howard “welcomed me with open arms”, even though she warned them in advance “that he wasn’t very well liked by the Aboriginal people”.

While in Bostock’s family Howard was a notorious figure, in Howard’s family he was known as someone who had tried to help the Aboriginal people under his care. Bostock came to two conclusions: the first is that history depends on who is doing the telling, and the second is that “they are no more responsible [for] what their ancestor did than I am [for] what mine did”.

“Mine were slave traders, so I felt a great feeling of peace. It was like a sort of washing away of grief because the family didn’t even know that he was involved in this. And they felt very terrible about it.”

But to have that peace, the truth needs to come out.

She believes the Aboriginal affairs department should not be “ferreting shit away”, limiting access to Aboriginal stories. “I’m fighting for the kids to know these stories, to know where they come from.” Borrowing from the words of Thomas DeWolf, a descendent of American slave traders, she says: “The history of Aboriginal people in this country is a living wound under a patchwork of scars. The only hope of healing is to be willing to break through the scars to finally clean the wound properly and begin the healing.”

When she was finishing her book, Bostock found herself in “a very peaceful place”. She has wondered “if family history research was the key to emancipation, because researching my ancestors’ lives has spiritually unshackled them”.

“I too am unshackled. I know their names. I know who they were.”

• Reaching Through Time: Finding My Family’s Stories by Shauna Bostock is out now through Allen & Unwin