Renee was working on a project about a crime when she realised she recognised the murderer.

Renee McBryde was researching a high school project when she discovered her father was a cold-blooded killer.

Until the age of six, McBryde was told her father was “working away” at the Cottee’s Cordial factory. Her father, double-murderer Michael Caldwell, called her every week from “Cottee’s” to check in.

During one of these phone calls, Caldwell told his six-year-old daughter he wasn’t actually working remotely, he was serving time in jail for a serious crime.

In a follow up phone call, Caldwell admitted to little Renee that he had killed two men.

McBryde’s mother then told the young girl her father had acted in self defense, that he was a “crusader”, and that she should never tell anyone about her father’s past.

“My mother told me no one would ever accept it, no one would want to be my friend,” McBryde said in an interview with 60 Minutes.

“She said I had his blood running through my veins. I understood why but it was tough because I felt like from that moment on, I couldn’t be myself.

“I had no idea about the gravity of what that secret was going to mean going forward, and how it would shape my identity.”

But McBryde would not discover the full extent of her father's crime for another decade. And it was a discovery she held close to her, keeping it secret, for many years.

When tasked with researching a crime for a high school assignment, McBryde decided to look into her father's past.

What she found was horrifying.

On a computer at the NSW State Library McBryde discovered her dad was not a crusader, he was not acting in self-defense, he had killed two innocent men in cold blood.

“Both men were found bound and gagged, and appeared to have engaged in sex shortly before their murders,” McBryde read in a newspaper report that day.

In 1981, when Caldwell was just 19 years old, he robbed and stabbed to death two gay men. His victims were Constantine Giannaris, Greek Consul General to Australia, and Peter Parkes, a gay activist and schoolteacher.

Caldwell was working as a male prostitute in Sydney's Kings Cross at the time and he was in a relationship with McBryde's mother. McBryde would later discover she was conceived around the time of one of the murders.

“One of the murders was committed just at the time I was conceived. I struggled with that as a teenager. As my life was beginning, someone else’s was ending at the hands of my father," she told 60 Minutes.

Caldwell, along with a 16-year-old boy, was charged and convicted for both murders. He has since been released from jail.

McBryde would later discover her mother was the 15-year-old girl who was charged with wilfully concealing knowledge of the murders, and that together they hid this sinister secret from her for years.

“As a child, so much of your identity is determined by who your parents are,” Renee said. “Who am I? What am I going to be like? How much of my parents is in me?”

Finding out about her past set McBryde off course for a few years. Since, she fell out with her mother, was a victim of sexual assault, and became trapped in an abusive relationship for 10 years.

For a long time the now social worker worried she was carrying the "killer gene". She worried that she, or one of her three children, could go on to commit a heinous act.

But as forensic psychiatrist Dr Jeremy O'Dea told 60 Minutes host, Liz Hayes, there's no "no clear generational transmission of murder either as a behaviour or gene".

"There's been very few people who are children of those who have been convicted of murder who go on to murder themselves," he said.

McBryde now lives in Alice Springs with her husband, John, and their three children. She works as a social worker and has dedicated her life to helping others.

The mum-of-three hasn't had a relationship with her dad since meeting him briefly after he was released from jail.

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