Brooks Way were absent from the first X Factor live show after one of the group was accused of sending threatening messages to an ex-girlfriend, according to reports.
The twins, Kyle and Josh Brooks, both 17, were due to perform as part of Louis Walsh's groups category alongside the other 11 acts in Saturday night's programme.
But their performance was pulled after a tip was "given to the show regarding one of the group".
Last week The Sun on Sunday reported Josh Brooks had been involved in an altercation with a girlfriend at a New Year's Eve party.
The singer told the newspaper: "A fight broke out between me and another male at a party. Amelia, along with others, tried to break it up.
"She was accidentally knocked in the process. It was never my intention to hurt her or put her in danger - and this situation is way out of my character."
As Saturday night's show opened, host Dermot O'Leary told viewers "due to circumstances the Brooks brothers will not be performing this evening".
The pair, initially called The Brooks and who also appeared on the show in 2014 when they left at the judges' house stage, were included in the ITV programme's opening montage.
An ITV spokesman said: "As was said at the top of the show, due to circumstances that have arisen Brooks Way won't be appearing tonight.
"This relates to information which has been given to the show today regarding one of the group."
During the show the pair tweeted from their official account, saying: "Such a shame we can't be there tonight ... hope everyone is enjoying the show." They later deleted the tweet.
The programme's first live show was dominated by controversial gangster rapper Honey G who performed last, singing her own version of Tupac's California Love.
Walsh said the late rapper "would be happy" with her tribute, but Nicole Scherzinger replied saying Tupac would be "turning over in his grave".
On Honey G's performance, Simon Cowell said: "I don't know what just happened ... but here's the weird thing, I loved it".
Novelty pair Bratavio are the early bookies' favourites to be booted off the show, with William Hill making them 11/10 to be leaving the programme on Sunday.
They performed a melody of 90s songs including Barbie Girl and Boom Boom Boom!! which was slammed as a "musical horror movie" by Cowell.
Up first were three-piece boy group 5am, who performed an energetic rendition of Justin Timberlake's Can't Stop This Feeling which got Scherzinger out of her seat.
Wildcards Samantha Lavery and Ryan Lawrie respectively performed Shontelle's Impossible and One Direction's Perfect , with Cowell commenting that "the wildcards are smashing it tonight".
Meanwhile Finnish singer Saara Aalto was mistaken as Norwegian by her own mentor Sharon Osbourne.
Introducing her act Osbourne said: "She's come all the way from Norway" before being shouted down by the live audience and fellow judge Louis Walsh.
20-year-old Gifty Louise was the first singer to perform an unreleased track with her version of That's My Girl by American girl group Fifth Harmony.
She was followed by Osbourne's act, Relley C from Birmingham who sang Shackles by Mary Mary which featured a short rap verse whilst Matt Terry's version of You Don't Own Me by Lesley Gore was lauded by the judges, although Cowell criticised his high notes.
Scherzinger disagreed, telling Terry his "highs had wings, they soared".
Freddy Parker's sombre rendition of Killing Me Softly by The Fugees also divided the judges with Cowell calling his choice to stand up from behind the piano during the performance "bonkers" and "crazy".
Parker - who changed songs at the last minute after advice from his mentor Scherzinger - hit back at Cowell, telling him he felt it was the "right part of the song to stand up".
Emily Middlemas sang the Chainsmokers' Closer, before Honey G's energetic performance rounded off the show and included her chanting "I say Honey, you say G".
The X Factor returns on Sunday at 8pm where the first act will leave the show after a public vote.