Louis, 22, and bandmate Zayn Malik, 21, caused controversy yesterday when a clip posted online showed them puffing on a lit cigarette while being driven through the streets of Peru.
The video has sparked headlines worldwide and deeply mixed reactions from the 1D fanbase, some of whom are not that bothered and others that are devastated.
Louis' father, Troy Austin, falls into the latter category.
The Doncaster-based hotel owner, who has not seen Louis in several years, told The Mirror that he was "worried" for his son after viewing the footage.
"It seems the fame and money have changed him. He's a different person to that person three years ago," he said.
Troy said he understood the huge pressure that must be on Louis and the band but chided his son for not remembering One Direction's young and impressionable fanbase.
"Their attitude in the video makes me cringe. It's very childish. They need a serious talking to. I don't agree with it but I smoked it too when I was younger. But you should never brag about it. He's got to think about his fans."
Troy said Louis had always promised him he'd never get tattoos or smoke, but now "he's gone the opposite way." He added: "I hope it doesn't get worse."
Louis and Zayn have yet to comment on the controversial video, while a rep for One Direction has only said it's in the hands of their lawyers.
The band couldn't escape the limelight last night, however, as they were on stage in Sunderland for the latest concert in their 'Where We Are' world tour.
It's believed the alleged marijuana footage was filmed while the band were in Peru on the South American leg of their tour. Fellow band members Niall Horan, Harry Styles and Liam Payne are not seen in the clip.
At the start of the video, Louis can be heard saying: " "Here we are leaving Peru, joint lit, happy days."
After spying a police officer driving past their car, he says: "He's having a look. He's thinking, 'I'm sure I can smell an illegal substance in there' and he's hit the nail on the head."
"I'm just wondering now, sitting here in Peru, will this come back to me?" he adds. "Who knows? Maybe. Maybe not."
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