He would be able to keep a lid on his feelings.

"I was thinking, I'm not one who's going to get emotional," he said last week on the eve of the show.

It wasn't an illogical response from a man with Fearnley's history - nine gold, nine silver and four bronze medals for marathons and long distance events at Paralympic, World Championship and Commonwealth Games between 2000 and 2018; crawling the Kokoda Track in 10 days and being a passionate advocate for people with disabilities.

But discovering extraordinary events in his family's past had him in tears more than once, he said.

"It is a really, really emotional experience," he said.

"I expected it to be very different to what it is."

Fearnley retired from international wheelchair racing after the Gold Coast Commonwealth Games in April, 2018 where he won gold in the marathon, silver in the 1500m event and carried the Australian flag at the closing ceremony.

Who Do You Think You Are? producers contacted him a short time later. The program takes famous Australians on a journey to discover their ancestors. Many celebrities find people in their past who can point to what drives them today.

Fearnley said yes to the show without having to think much about it.

"I got sent an email out of the blue asking whether I would take part and I just thought, 'This is very cool'. I jumped at the chance. It was too good to pass up."

For two weeks one year ago he travelled by car around parts of NSW - from central west NSW to south of Canberra near Cooma and back to Sydney - to tell his family's story.

And what a story it is.

There's a convict, but not just any old convict.

Seven generations back on his mother Jackie's side of the family is an extraordinary woman known as Catherine O'Hearn, or Catherine O'Sullivan, or one of eight other names that made her famous and infamous from almost the minute she landed in Australia in 1813.

"She was just a wild adventuress who came over here as an Irish Catholic convict. I don't know why she was sent out, possibly for stealing food, but she was amazing," Fearnley said.

"She lived a tortured life but she just kept bouncing back. The convict part of her life and why she got here was probably the least interesting. There was a lot of adventure out here in Australia for people like Catherine. She found adventure."

There is a moment in the show when Fearnley is introduced to his convict ancestor via an article in a newspaper, the Parramatta Gazette, about a group of women known as the "Amazonian Bandidi."

"She's there on my mother's side, seven generations back. I'm here and suddenly introduced to this fierceness and rebellion in a woman I am directly related to. That's the unrest that sleeps in you.

"It sounds like my daughter Emilia, who was about six months old when we were filming this but who's now 18 months old."

Fearnley, a teacher, said his knowledge of Australian history from school was probably the same as many people's - big on dates of famous events like the landing of the First Fleet, but lacking in the richness of Indigenous history and the kind of detail that would bring the story of Australia's development alive.

Like the story of his Amazonian Bandidi great great great great great grandmother with the 10 aliases.

"Without these stories there's a disconnect of the generations. The stories that should have been told to kids are just lost," Fearnley said.

"I knew very little about Australian history because you spend so much time just looking at what's in front of you that you don't have time to think about the past. Part of the reason I agreed to be on the show is because it explores the richness of Australia's past and it does it in a way that makes it exciting and interesting.

"On my mum's side of the family we didn't really know much at all about the history, and now there's this person in our past I'm really glad to have known. I feel so happy there's this link to this powerful Australian woman."

Then there's the sadness of uncovering the lives of men who served during World War I and the legacy of war on the families who supported them.

The story of Fearnley's grandfather Harry and great grandfather Charles were "the biggest surprises" of the show, he said.

"On my dad's side I had an idea why we came to Australia, but the show just unpacked a lot more."

Fearnley's father Glenn's family came to Australia from the north of England after World War I.

While Fearnley is known to the world by his first name, Kurt, to his family he is Harry, the middle name given to him in honour of his paternal grandfather.

Discovering the detail of Harry and Charles Fearnley's lives was unexpectedly rich, sad and emotional, Fearnley said.

"One of the things that got me was how we lost our great grandfather. What we knew just wasn't accurate."

Charles Fearnley was a man with a real sense of duty, Fearnley said.

"He was middle class but signed up for service the day after 60,000 died in the Battle of the Somme."

The stories of Harry Fearnley that came down through the family were of a very disciplined man, but "the character I was introduced to (in the show) was very honourable and very gentle".

Letters written by Charles Fearnley to his wife pierced the public persona of a man who'd experienced the unimaginable trauma of war to reveal a loving and sensitive person.

"It was brutal what people went through during the war, and then to hear the circumstances of their deaths, that was one of the most emotional parts of doing this for me," Fearnley said.

The story of Fearnley's paternal forebears is also the story of one part of Australia's migration history, when waves of people from wartorn parts of the world turned to Australia for peace and a better way of life for their children.

"There was one person in our family buried in the north of England, and the others found themselves on the other side of the world," Fearnley said.

"It was really hard doing the program, but it's been a really nice thing for our family to get to know so much about our past. The show is about telling the untold stories of people whose stories have been forgotten.

"Doing the show was such an intense experience. You don't know where you're going from day to day. You're in a bubble for two weeks. You feel like you're in a live play and people are just turning page after page in the story of your life.

"I was in it every day but I haven't seen it. I'm really looking forward to seeing what it is. There were emotional parts but it was a year ago now. I'll definitely be watching to see what they've left in and what they've left out."

Telling Australian stories has opened up another side of Fearnley's life.

In April last year, the day he arrived home after his last international race, he bought film production gear and worked out a plan for his own podcast, Tiny Island.

In each 30-minute episode he speaks to Australians about their passions, what makes them tick and what it means to be an Australian. The series started with champion surfer Layne Beachley and has included actor Georgie Parker, Anglican priest Rod Bower, The Wiggles and University of Newcastle associate professor Kelvin Kong.

He has 16 so far and is aiming for 100.

"I'm no historian but I'm getting different takes on what it means to be Australian. It's the right time. Whether it's sport, politics, the media landscape, we're in such a moment of change.

"Podcasts have been an idea I've had for years. Just sitting and talking to people. When you look around at the moment I think it's not a bad idea. Maybe it would be helpful if we all just sat back and talked for a bit."

READ MORE: