The teenager's father had a long Aussie Rules history after growing up in Melbourne before he shifted interstate and captained New South Wales.
So in his last year at school, Byrne ended up playing rugby on Thursday, Aussie Rules on Saturday and league on Sunday.
He made an Aussie Rules rep side as a ruckman and centre half forward and signed a contract as an interstate player and headed off to Melbourne.
"I was lucky I was in a really good team and that helps when it comes to selection," he said.
Byrne went to the Melbourne club, subsequently Hawthorn where he won a Grand Final winner's medal, and the Sydney Swans in a 167 game career over a 13-year career.
His playing done, Byrne began studies in financial planning and working in small business development.
He was still keen on coaching any of the winter codes and through common friends he met Kiwi league captain Mark Graham who had been used by the Swans to help them with their tackling techniques.
Graham was coaching league at Manly and asked Byrne if he could help his players kick and catch like Aussie Rules players. A session a week with league men like Cliff Lyons, Geoff Toovey and Owen Cunningham worked and when Graham shifted to coach at North Sydney, Byrne helped out there too.
His reputation spread until he helped out at the Manly rugby club where future Wallaby coach Tim Lane was coaching.
Mick the Kick, Two Metre Mick or Mick Dundee as the Blues rib him, was on his way into rugby and fulltime work as a kicking and skills consultant.
His skills have taken him to work around the globe in Australia, South Africa, England, Japan, Scotland and connections with men like Tony Gilbert, Wayne Smith and Jim Telfer.
"I learned a lot from Tony, he was an educator while Jim taught me massive amounts and grew my knowledge about forward play." Byrne said. "They were both great mentors for me about what went on up front.
"I really enjoyed the unshackled freedom of skills coaching in rugby union. Just focusing on helping the players was great."
Gilbert's influence in New Zealand drew an approach from the NZRU and inquiries about Byrne's interest in helping the All Blacks improve their skills.
"They wanted a kicking coach but I had done that for a while and this was 2005 and I had broadened my work range," he said.
Working with New Zealand rugby players was a big drawcard though and much closer to his Manly origins than Edinburgh or Tokyo. Byrne persuaded the NZRU he was better value as a skills coach and kicking instructor.
Subsequently Byrne met Graham Henry. The conversation was crisp.
"So kicking coach, what can you teach me?" Henry inquired. The answer was equally to the point.
"I have never met a defensive coach I can't outkick," Byrne said and the pair were soon in deep conversation about plans to improve the All Blacks' skills and a range of programmes to suit age-grade players.
Byrne works on a broad range of abilities with the All Blacks and position specific skills. He helps with throwing, lifting, kicking and in his first season with the Blues, he also has a roving commission.
His priority though are the forwards and that is a first for the 54-year-old career coach.
"I am a technical and tactical coach with the Blues with an emphasis on the forwards, the breakdowns and kicking. The thing with JK [Kirwan] though is that we all help each other."
It is a jigsaw and there are times when Byrne will go and look at the backs' attack and Grant Doorey will come in to question some scrum ideas.
How does Byrne find his move to teach the men with single figures on their jerseys?
"It feels natural," he said. "I have been coaching in rugby since '97 and had two great forward mentors in Scotland. I am passionate about coaching and I am learning all the time."
Byrne still has notes and discs from his early days coaching rugby and checks himself against those ideas.
"Everything evolves but there is still a core that does not change," he said. "We went to a multi-phase game for a while but that has been shortened up now. The core responsibilities in the game have not changed at all."
Connecting with a Blues squad with many players new to Super 15 rugby is a change but Byrne just adapts his teachings. Some players are more receptive than others.
"Every player wants to get better," Byrne said. "It is a matter of working out how to achieve that. Each player has an individual plan with a list of areas to improve.
"My job with the Blues and the All Blacks is always to make every one of them better. You can help them all, give them ideas, things to think about and use to improve their skills," he said. "We have to give them teachings which they can connect to their game."
"Better never stops is our key phrase at the Blues and I love that because it is me and my coaching philosophy. We have to work on habit-changing ideas all the time."
Coaches have to be on top of their game, offer both instruction and levity in their work. They have to be counsellors and teachers, ogres and supporters.
Byrne relies a lot on Blues video analyst Troy Webber for data to assist his lessons and the preparation he does in the months before Super 15.
"With all these things the key is to work bloody hard, stay on top of your area then as a coach you can absorb what is happening around you a lot better."
