The Olympian, 27, announced this week that he had split from his girlfriend Eirianedd Munro, apologising to her for "letting you down".
It came a year after he competed in the BBC ballroom contest, where there was speculation that he and his pro partner Katya Jones came close to kissing at the end of their Argentine Tango.
Many suggested Adam’s love split was part of the so-called Strictly curse, which has seen a raft of stars splitting from their partners after being on the show.
But his brother James told MailOnline it wasn’t the case.
“He was in it over a year ago,” he said.
“It has nothing to do with Strictly.”
James also told the publication that the split was "amicable”.
“I was surprised that it happened but sensed it was coming,” he said. “But Adam’s doing OK. It’s his gladiator mindset.”
Adam, who has 23-month-old son George with Munro, posted a message on Instagram this week saying: “Eiri and I have decided to go our separate ways.
“We have enjoyed a wonderful three years together, 2 of those with our gorgeous son George.
“Our priority has always been to provide the happiest and healthiest home environment for him, and right now that means ending our romantic relationship. I could not ask for a greater mother for George and I am so grateful to Eiri for her amazing support over the last three years. Eiri and George, I’m sorry for letting you down.”
He added: “My only interest is for the well-being of our family at this difficult time so I ask that our privacy is respected and I won’t be saying anything further.”
Adam and Jones’ passionate Tango was one of the talking points of the last series of Strictly, but the swimmer tweeted that he would “not be overcome or lowered by your gossip”, telling people speculating about it: “Protect your energy."
Munro later poked fun at the whole thing in a video posted on TikTok.
She pretended to cry in the clip and captioned it: “Watching your boyfriend almost kiss another woman on live TV.”
Throwing her head back, she added: “Finding out 10 million other people also watched it live."
Watch: Adam Peaty says son George is sportsperson in the making