It is a family affair in Phoenix, where two boisterous, bearded brothers have dominated the build-up to what has been dubbed the Kelce Bowl.

Jason and Travis Kelce will be the first siblings to square up on American football’s biggest stage as the Philadelphia Eagles take on the Kansas City Chiefs in Super Bowl LVII Sunday.

At 35, Jason is the older, quieter one. Extravert Travis is prone to diamond earrings, Louis Vuitton jackets and ebullient touchdown celebrations.

In the NFL the brothers are equally respected, feared and revered. Each is regarded as the best in their position and both have one Super Bowl win under their belt.

Jason has been Philadelphia’s center for 12 years. A rock in the heart of their offensive line, he is a specialist run-blocker who is adept at marginal gains.

In a game of inches, Kelce is central to the Eagles tactic of using a rugby-style maul to help quarterback Jalen Hurts complete short-yard gains. In the regular season, the Eagles successfully converted 29 of 33 sneaks into first downs.

He is the highest paid center after signing a one-year, $14million deal to carry on his career in the City of Brotherly Love.

Travis is two years younger and has an unerring ability to be elusive despite his six-foot-five frame. He can catch any ball and then run considerable distances, with or without players trailing from his limbs and torso.

In the regular season he is unstoppable – he completed his seventh straight 1,000-plus yard season, extending his record for a tight end.

But in the postseason he is a phenomenon. In 17 playoff games he has 127 catches for 1,467 yards and 15 touchdowns. Only Jerry Rice, the greatest wide receiver of all, has more (151 catches for 2,245 yards and 22 touchdowns in 29 playoff games).

Chiefs quarterback Patrick Mahomes, who was voted MVP for the second time Thursday, was in no doubt as to his historical significance. ‘Travis, I mean, it’s Travis, greatest tight end of all time,’ he said in November.

The Kelces were always close. Growing up in a sports-mad house in Cleveland Heights, Ohio, Travis idolized his older brother. He chose to wear No. 87 in the NFL as it was the year of Jason’s birth.

In September, the brothers decided to launch a weekly podcast, New Heights. After 26 episodes it tops Apple’s podcast charts.

‘It’s almost been like therapy, man,’ Travis said. ‘It’s been cool to hear what he’s going through and just to have some fun with my brother like we did back in the day.’

‘We get to talk to each other every week, we get to have fun and in some ways I feel like it’s made my brother and I closer, talking every single week,’ Jason said. ‘Normally in the course of a season, you go months without talking to each other at times. You’re so caught up in your own stuff. This ended up being a great thing.’

Their parents have also appeared on the show – and regularly threaten to steal the limelight. Divorced in 2011, the pair remain close and frequently attend games.

Last season mother Donna traveled 1,200 miles to see both her sons play on the same day and gave Jason and Travis homemade cookies to get through Monday night’s media duties.

On Sunday she will be sat in NFL commissioner Roger Goodell’s box wearing her custom-made half-and-half jersey. The front is red and adorned with Travis’s No. 87; the back is green and features Jason’s No. 62.

Father Ed, 71, will be cheering both sides from the stands. A former steel worker, he encouraged his sons to play any sport as they grew up in a Cleveland Heights, Ohio, in a house full of broken windows, balls and vast eating bills.

There were fights too. Plenty of them.

'Jason won all the fights but one, and that was the last fight,' Travis said this week. 'I’d be silly to say that I won. But I definitely gave it my all and he stopped fighting me after that.’

Jason also played hockey and lacrosse, as well as the saxophone, while Travis veered toward baseball and basketball.

But the Kelces always dreamed of playing in the NFL for the Cleveland Browns and both excelled at the sport.

In 2008 Travis joined Jason at the University of Cincinnati. He was banned for his second year after failing a marijuana test, but after an intervention from his role model older brother, the siblings played on the same team for one season.

Jason was drafted by Philadelphia in 2011 in the sixth round by then head coach Andy Reid. Two years later, Travis was picked by Reid in his first season as Chiefs head coach in the third round.

Both are firm fan favorites. During the Eagles Super Bowl-winning parade in 2018, Jason embarked on a five-and-a-half minute, profanity-laden speech outside the city’s Art Museum.

Since 1901, Philadelphia residents have dressed up as Mummers to celebrate new year. Kelce donned a green genie costume and bellowed in a husky baritone: 'This entire organization is a bunch of driven men who accomplished something.

‘We're a bunch of underdogs. And you know what an underdog is? It's a hungry dog...'

Travis is normally as animated postgame. He prodded Cincinnati’s mayor – who had predicted a Bengals win - after the AFC Championship game.

‘Hey, I've got some wise words for that Cincinnati mayor,’ he said. ‘Know your role and shut your mouth, you jabroni!’

Yet he has been careful not to poke his brotherly bear before Sunday.

‘You won’t see me talking too much trash with how much respect and how much I love my brother,’ Travis said. ‘But it’s definitely going to be an emotional game.’

Not half. Also in the stadium will be Jason’s two young children and his wife, who is 38 weeks pregnant. She will be alongside two obstetricians.

‘That could be a super Kelce Bowl. If she has a baby in the stadium, it’s officially scripted,’ said Jason.

If you’re looking for an omen, the Kelces have played each other three times – Travis and the Chiefs have won all three.

And yes, the Kelces have been thinking of what the end will bring.

Travis asked Ed which son he would seek out first. ‘Probably the loser,’ he said. ‘Somebody's gonna feel pretty crummy and I wanna be with him — initially.’