Australian comedian Denise Scott uncovered some uncomfortable family secrets on the most recent episode of SBS series Who Do You Think You Are?  Tuesday’s episode opened with Denise, 65, visiting her older sister Julie as she embarked on a journey to find out more about their mother Margaret’s early life.

Denise’s mother was born to Ellen ‘May’ Bock in October 1924, who was aged just 15 at the time. However Margaret was raised to believe that May was her sister, and her grandparents Albert ‘Pa’ and Margaret Bock were her parents.

“My mum was 15 when she found out that her sister was her mother,” Denise said

The show followed Denise to South Australia, and then on to Victoria, as she attempted to find out more about her great-grandfather Pa Bock, with the Studio 10 star admitting she holds him responsible for the family secret that cast a cloud over her mother’s life. In Victoria, Denise discovered that Pa Bock essentially severed all ties with his own German Lutheran parents when he made the decision to marry Irish Catholic Margaret Daly in the Catholic church.

Two years after his father’s death, Pa set up a saddlery business, however he went bankrupt three months later which left him with no choice but to sell the family’s belongings.

“He must have been so ashamed,” Denise said. “I think shame can be passed on and you can carry a family’s sense of shame. Pa Bock was not a very warm person, [and] maybe in order to survive.”

Later in the episode Denise discovered that her mother’s family relocated following Margaret’s illegitimate birth in a bid to cover up the fact that teenage Ellen was her biological mother. However Denise was then shown records which showed that Ellen actually gave birth six months after her own mother’s death in April 1924.

“So when Pa Bock’s wife Margaret dies, she couldn’t have been passed off as the mother,” a historian told Denise. “The only way they could have done it is if they moved and turned up in a new location with the baby. And then in the new location he presents himself as her father.”

The historian, who described the rouse as a “really amazing cover-up”, added: “We’ve got Pa Bock here with mixed motivations, but not all negative ones. The shame was not only on the mother who had the child, it was on her father because fathers were meant to deliver their daughters safely into marriage, virginal.

“He’s potentially going to be shamed by this too, and it would have much more difficult for your grandmother to go on and build a life if the secret had come out that she’d already had a child. And it also would have been difficult for your mother to grow up with the band of illegitimacy on her.”

Following the discovery that Pa Bock had actually been “trying to save them all from shame”, Denise said: “I’m sad for Pa Bock, he seems to have done what he can to save his family. I hadn’t understood or appreciated that about him before.”

She added: “It also makes me think more about the stigma for the female because when my mum was 14, she was sexually assaulted by two of the boys from a wealthy family in town. She was going to keep that secret but May, my grandmother, saw my mum trying to sneak in with her clothes ripped. And it was May who insisted those boys go to court.

“I always thought it was amazing that May was prepared to take this to court. That was the ferocious love of a mother. Somehow to me it all connects.”

You can watch Who Do You Think You Are? on Tuesdays at 7.30pm on SBS. Next week’s episode stars award-winning actress Kat Stewart.