Not all twins share a tight bond, even those who grew up together pushing each other to sporting stardom.
Australia's most famous twins, Steve and Mark Waugh, were hardly matey during their test cricket careers and even disliked being photographed together - a result of sharing a bedroom for 17 years.
Rugby's most famous twins, Mark and Glen Ella, did get on well off the field as well as on, where they bamboozled defenders with their sublime skills and almost telepathic understanding.
But not even the Ellas' brand of brotherly love can compare with that of the Wallabies current twin combination - Saia and Anthony Fainga'a - who admit they're more like an old married couple.
For one, backline marvels Mark and Glen wouldn't have been caught dead braiding the other's hair before a game.
It's a pre-match ritual centre Anthony quietly performs on hooker Saia, the older by five minutes, each time they suit up for the Super Rugby pace-setting Queensland Reds.
It certainly took grizzled former test prop Ewen McKenzie, who staunchly believes front-rowers should sport crew-cuts and cauliflowered ears, by surprise when he took over as Reds coach last year.
"I couldn't quite fathom that but once you meet them you see how they function and it becomes quite obvious," says McKenzie. "There's all these little things that go on to show the bond they have, and there's benefits of that."
Not only are the 24-year-olds twins; they're best friends, housemates, share a Twitter account and are hardly ever far apart.
"People ask 'do you get sick of each other?' But you can't really get sick of your best mate," Saia says. "We're so close and everything we've done we've achieved together and we've pushed each other to the limit.
"We're like an old couple really and people ask 'what are you going to do when you get wives? Are you going to have houses next to each other?'.
"It's all fun but we love being in each other's company, and family comes first no matter what."
Indeed the longest the Canberra-born pair, two of four boys born to Samoan couple Saia Snr and Cindy, have been separated was for two weeks when Saia travelled to South Africa with the Brumbies in 2008 when Anthony was recovering from knee surgery.
"It's corny but we still spoke to each other every day on the phone," Saia admitted.
It contrasts with the Waughs who never roomed together or spent time alone on tour, nor talked while batting.
The Faingaas' relationship not only raises the odd eyebrow, it's drawn admiration of Reds teammates, especially as Saia sacrificed a longed-for career with the Brumbies to stay with his unwanted brother.
"The Brumbies hadn't offered me anything and the Reds did," Anthony recalled. "Saia made the gamble and said 'Anthony, I'm not going to stay down here I'll come with you. We both signed here and haven't looked back.
"For us it was a no-brainer to come together."
While the gamble paid off last season when both twins, renowned for their body-on-the-line play, were key ingredients in the Reds resurgence under McKenzie to debut for the Wallabies, 2009 was a year to forget in Brisbane.
Although they were lured to Queensland by their former Australian under-19 coach Phil Mooney, who made them captain and vice-captain of his 2006 world champion team, they were bench bound and hardly received a chance under Mooney at the Reds.
"Our first year wasn't the greatest," Anthony admitted. "I think it was quoted we were 'the worst investments Queensland rugby has ever made'. The next year we made the Wallabies.
"You look now, we're top of the table. The tables have really turned."
Like the Ellas, the Faingaas are identical twins but are far easier to distinguish thanks to the demands of their positions on the rugby field.
Both played as back-rowers early in their schoolboys days at St Edmund's College where Anthony joined Ricky Stuart as the youngest student ever to play first 15 when he was selected in grade nine.
But coaches told Saia, always slightly larger than his twin, he needed to become a hooker if he wanted to play for the Wallabies, while Anthony was moved into the centres.
Now Saia weighs in at 107kg, certainly not on the big scale for a hooker, while Anthony is a slim-line 92kg.
"People ask what happened to you and I always say I think I ate too much bread when we were young," Saia says. "We are identical; I hate to say it, but we are.
"He's quicker but when we were younger he did all the running and I did all the tackling, and now it's swapped over - I run into the brick walls and he does all the tackling."
Their Reds' contract expires at the end of next year and the pair are determined to remain as a Team Fainga'a package.
While Saia has defied his coach by keeping his braided hair long, McKenzie is as big a fan as they come of the popular Reds standard-bearers and it's hard to see them leaving Ballymore anytime soon.
But can they play out their entire professional careers together?
McKenzie thinks it's possible: "Everyone is looking for good players and they're both good players ... they've managed it so far".
Fainga'a FACTBOX
SAIA Fainga'a
Born: Feb 2, 1987
Height: 187cm
Weight: 107kg
Position: Hooker
Test caps: 11
Test debut: 2010 v Fiji in Canberra
Super Rugby caps: 63 (36 Reds, 27 Brumbies)
Super Rugby debut: 2006 v Stormers for Brumbies
ANTHONY Fainga'a
Born: Feb 2, 1987
Height: 182cm
Weight: 92kg
Position: Centre
Test caps: 4
Test debut: 2010 v New Zealand in Melbourne
Super Rugby caps: 37 (33 Reds, 4 Brumbies)
Super Rugby debut: 2007 v Bulls for Brumbies
