The Hobbs siblings are taking part in the Sydney to Gong bike ride - the very same event their father James used to do before he was diagnosed with MS in 2004.
Annie and Jack Hobbs have entered tomorrow's race, which is a fund-raiser for MS, and they'll be joined by their sister Jennifer Hobbs, who is coming up from Melbourne to take part.
Their mother, Annette Hobbs, said her husband had felt there was something "not quite right" for about 15 years before getting the MS diagnosis from his neurologist.
And it came as a relief - at least he knew what was wrong with him.
He has been handling the neurological condition quite well, Mrs Hobbs said. His lifelong love of fitness, which has been passed on to the pair's children, has helped to ease the symptoms of MS.
While he hasn't entered the Sydney to Gong ride in years, James still rides his bike regularly and is known to nip down to the beach after work for a swim or a surf.
For Jack, this is the second straight year he's entered the Sydney to Gong ride and he'll be doing the full 90-kilometre course from St Peters.
Annie, however, is entering her first Gong ride and has opted to take it relatively easy, tackling the shorter 58-kilometre course.
"This year I got a bike so I thought it'd be good to do the ride and dad has MS, so I thought it'd be a good cause to get into," Annie said.
Jack said he had been doing some training for the ride, but "I'm doing it with my sister this year, so I haven't done as much".
It sounds like sibling rivalry, but Annie said they already knew who would arrive at Stuart Park first.
"He's going the full distance and I know he'll beat me anyway," she said.
James and Annette will be at the finish line and, with Jennifer up from Melbourne, a family celebration afterwards might be on the cards.
"I think we're all going to go out for lunch as a family," Jack said. "Or afternoon tea."