St George Illawarra star Tyson Frizell has expressed pride that the brother he was prevented from growing up alongside in Australia is now following in his footsteps by making a name for himself on the professional sporting stage.

Shannon Frizell is being touted as a future All Black after scoring a try in his Super Rugby starting debut for the Highlanders last month and grabbing a hat-trick the following weekend but like Tyson, who was a member of Australia’s World Cup-winning team, he is also eligible for Wales and Tonga.

In a twist on the age-old nature versus nurture debate, the brothers were forced to grow up separately as Shannon, who is two years younger than Tyson, was not allowed to live with his adopted family in Australia.

However, they were still able to maintain a close relationship as Tyson would regularly visit Tonga with his parents, Andrew and Sophia, and younger brother, Zion-Mateo, to spend time with Shannon.

"It is something that is pretty common in Tongan culture, to adopt a kid from another family, but he wasn’t able to come over and live with us," Frizell told NRL.com.

"My mum fought hard at that time to get him over but wasn’t allowed for some reason. The immigration laws stopped him coming over and that is why we spent so much time over there at that time, so we could be with him.

Shannon and Tyson Frizell. ©NRL Photos

"We used to go back to Tonga twice a year to hang out with him and see the family over in Tonga."

In Tonga, the brothers would play rugby union together, while Shannon went to school with Warriors centre Solomone Kate and Titans star Konrad Hurrell.

Their mother, Sophia, is from the same village, Navai-Folaha, as the mothers of Parramatta centre Michael Jennings and former Melbourne and Broncos star Israel Folau, who now plays for the Wallabies but is believed to be considering a return to the NRL.

However, 26-year-old Tyson said neither he or Shannon, 24, considered they would play either rugby code at an elite level.

"I used to go over there and play in village tournaments with Shannon when we were about 14 or 15," the Dragons second-rower said.

“I was a big, tubby thing and he was a tall, skinny thing but nothing like that was ever thought about and I don’t think we ever imagined being where we are today or even thought it was possible.

"I think we both just grew up playing footy and we enjoyed footy. I don’t think we ever thought we could make a career of it. It wasn’t spoken about at all. It probably seemed like something that was too hard to reach.

"Konrad Hurrell has come from Tonga and he is doing well and Shannon also went to school with Solomone Kata but growing up in Tonga, there is not really any opportunity at all to have a career in sport or anything like that.

"I have been very lucky to get to where I am now and I guess Shannon is just starting what will hopefully be a long and successful career. It is good to see kids who come from a small island like Tonga be able to make something of their lives through sport."

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Frizell could also have chosen to play Super Rugby but he turned down an offer to join the NSW Waratahs academy after representing Australian Schoolboys in 2009 to sign with Cronulla.

The potential loss for Rugby Australia is now two-fold as Shannon does not qualify to play for the Wallabies, but he is eligible to play for Wales through Swansea-born Andrew.

"Dad was able to get him a British passport and he is able to do whatever he likes now," Frizell said. "Wales is a massive rugby country and he could play for Wales, he could be an All Black or he could play for Tonga."

Tyson played for Wales in 2011 and 2013 and the NSW Origin forward revealed he had been in discussions to represent them again at last year’s World Cup if he wasn’t selected by Australia.

Despite his grandfather being a founder of the Tongan community in Wollongong, Frizell said he had not been approached to join the likes of Jason Taumalolo and Andrew Fifita in playing for the Mate Ma’a, but was already committed to Wales.

"Even though they weren’t really strong, I was in contact with Wales and I was going to go and have a World Cup for them if I didn’t get picked for Australia," he said.

"I just felt at that stage that Wales were the ones who gave me the opportunity to play international footy when I was 19 and I had played in the last World Cup for them.

"Look at the impact Jason and Andrew had for Tonga. You never know I might have had an impact for Wales, and maybe helped grow the game in Wales."

We used to go back to Tonga twice a year to hang out with him and see the family over in Tonga.

Tyson Frizell

However, the Corrimal Cougars junior hasn’t ruled out playing for Tonga later in his career to honour his large Tongan family in Wollongong, who regularly attend Telstra Premiership matches to support him.

"My grandfather’s nickname is 'Captain' because he says he is the first Tongan to come to Wollongong and my mum is the eldest of eight children, so I have got lots of cousins and first cousins in Wollongong," Frizell said.

"I love my Tongan side and I have grown up with Tongan traditions but Australia will always be my No.1 choice and my parents know that.

"I guess one day they might want to see my put on the red jersey [of Tonga] but for now I love wearing the green and gold and that is all I want to be doing."