"It all started at the Mt Albert Lions," said Cleary senior. "Nathan played his first game of league in Auckland in an open weight game. I asked him how he went and it didn't go so well and he wasn't too keen to front up again, so he was lucky his second game was in the restricted weight group and off he went. If it wasn't for the restricted weight category, he wouldn't have been playing there, so who knows, that might have been the catalyst for his career."
After his rocky start, Nathan quickly found his feet playing boys closer to his own size, despite being two years younger than many of his teammates in the Mt Albert under-13s.
Under the guidance of veteran coach and renowned talent spotter John Ackland, he grew in confidence and ability, and began learning the attacking and organising skills the Blues will rely on as they search for their first Origin series win since 2014.
"He [Ackland] had a really good feel for not just coaching rugby league but coaching kids, and because it was restricted weight, he had to actually coach them instead of relying on power and strength," he said.
"One of the good points of the restricted weight category is you still had to play against older kids, so there's still that intimidation factor, there's just not ridiculous variances in weight. He got a good base and understanding of the game from a young age and John certainly helped with that."
Ackland said it was obvious early on that Nathan was destined for big things as he shared his father's talent, poise and natural kicking ability.
"It hasn't surprised me that he's kicked on," said Ackland. "Nathan's always had outstanding basics with very good skills and a passion for the game. Normally those three things are enough.
"He's always had very good hands, and with his soccer background, he's always been a terrific kicker.
"He's obviously got a love for the game and a good, calm head. He has his father's cool temperament.
"Most importantly, Nathan has probably had coaches who have believed in him, the most important thing any young player, but especially halves, need when starting out," said Ackland.
That grounding put him in good stead before he rounded out his footballing education in Penrith's tough junior system, after Ivan started coaching the Panthers in 2012.
"Nathan's club team wasn't one of the better sides, so he always had to learn to lose and to find a better way than having big guys steamrolling teams," said Cleary. "He was able to also play in strong Penrith junior rep teams as well, which helped."
Ackland had no doubts Nathan would handle the step up into the Origin arena, as he'd always shown an ability to withstand tense situations.
"I was at their place one night and he kicked the ball right through the TV," he said.
"He wasn't fazed by that and was fairly unflappable. Ivan was fairly unflappable, too, but [Nathan's mother] Rebecca was pretty pissed off."
The proud parents will make the trip to Melbourne for the biggest night of their son's career, while Ackland will be cheering him on from this side of the Tasman.
"I'll swing down after training and enjoy the game," said Cleary. "I hope I can enjoy it, I'm pretty nervous. He'll be all right, he won't let anyone down."