It’s tough to play favorites when it comes to the members of One Direction. There’s Niall Horan, Zayn Malik, Liam Payne, Harry Styles and Louis Tomlinson — also known as the cute one, the cute one, the cute one, the cute one and the cute one.

That uniform distribution of talent and charm might explain why the British-Irish boy band is surfing a tsunami of hype. After placing third on the 2010 season of “The X Factor,” Simon Cowell’s British version of “American Idol,” One Direction’s puppy love anthems colonized the iPods of tweenage America.

The quintet bounced onto the Patriot Center stage in Fairfax on Thursday night as if its members had been shaken out of a J. Crew catalogue. Hair tousled, smiles beaming, they spent 80 minutes onstage being as likable as they could be, each member pulling the same weight, sharing the spotlight and the microphone.

But their harmonies were barely audible at first. The capacity crowd’s screaming spiked to surreal volumes, drowning out entire bars of the show-starting “Na Na Na.” According to Patriot Center staff members, the wailing clocked in at 122 decibels. That’s louder than the roar at Verizon Center after a Caps goal, louder than a heavy-metal concert, louder than an ambulance driving past a lawn mower in a thunderstorm.

Even if shrieking young fans lost a little of their hearing and all of their voices Thursday night, they didn’t lose a nanogram of their innocence. That’s because One Direction’s lyrics are all hugs and smooches, with barely a trace of the sexual hint-hinting you’d hear in a Justin Bieber song. Their Britishness makes them seem a bit dashing, a little mysterious but, above all, exceedingly polite.

And doesn’t every generation deserve five well-mannered young men to ferry them across the raging hormonal rivers of puberty? Along with groups Big Time Rush and the Wanted, One Direction is part of a new wave of boy bands that echoes the millennial heartthrob gold rush that brought us ’N Sync and the Backstreet Boys — and their ’80s forebears, New Kids on the Block, New Edition and Menudo.

But at the Patriot Center, One Direction appeared to be the boy band having the most fun since the Monkees. Over the course of umpteen songs, its members didn’t work the stage so much as loiter on it. They looked comfortable. No silly choreography, just a few ensemble fist-pumps. No ridiculous costumes, just letterman jackets, cardigans and khakis.

A no-nonsense backing band — guitar, bass, keyboards and drums — provided steady renditions of nearly all of the songs on the group’s debut album, “Up All Night,” as well as a few covers, including Kings of Leon’s “Use Somebody” and Natalie Imbruglia’s “Torn.” As the five traded couplets, it was tough to imagine a future Justin Timberlake, Ricky Martin or Bobby Brown emerging from the pack. No one voice stood out.

But if you watched closely, Horan seemed the most at ease. He kicked off “Everything About You” by pantomiming a golf swing and eventually played a little air guitar, much to the delight of girls sporting customized “I [heart] NIALL” T-shirts.

Reservoirs of craft-store puffy paint were depleted in anticipation of this concert. More than half of the audience appeared to be wearing homemade shirts, many emblazoned with personalized declarations (“Mrs. Harry Styles”), wiggly, hand-drawn “1D” logos and Union Jacks circumscribed by hearts, Sharpie on white cotton.

When the quintet vacated the stage to change shirts, video screens lighted up with montages. The first showed the group frolicking on a beach. The second showed the guys settling in on a fictitious college campus. And the third showed them lazing around a snowy cabin. Fans responded to the clips with the same enthusiasm they unleashed during the evening’s strongest songs, radio singles “One Thing” and “What Makes You Beautiful.”

Still, the videos’ seasonal themes raised a question: Will these girls have grown out of these tunes come next spring? One Direction certainly hopes not — the group has tour dates booked through August 2013.

As confetti snowflakes fell during the concert’s closing sequence, the singers lobbed fake snowballs into the seats, an act of playful reciprocity after being pelted with objects all night. There were stuffed animals, glow sticks, flags, baseball caps — and during a fizzy rendition of “Up All Night,” something you’d never expect to see flung onstage at a concert this wholesome. A bra.