The Dubliner (23), who works in social media marketing, exited the show last Friday after failing to find a romantic connection with any of the girls in Casa Amor.
He revealed this morning how it was his ‘Dancing with the Stars’ sibling (21), a model and an actress, who was head-hunted by producers to take part in the popular programme.
“Originally, they asked my sister Missy to do it some time at the start of last year. Then my family were like, ‘Jack, why don’t you do it?’ And I was like, ‘Why don’t I do it?’
"So I had to do all my bits and pieces and a couple of months later, I'm doing the show so it was pretty crazy,” he said.
“She (Missy) definitely thought about it. But I don’t think it’s something that she would be up for. Obviously she did DWTS this year but I think she wants to go down the acting route and stick to her own little path.”
He told 98FM's Big Breakfast with Rebecca and Brendan how he kept the news of his appearance on the show under wraps for the first month.
“I actually didn’t tell anyone, I didn’t tell my mum or my dad or anyone in my family. I didn’t tell anyone until pretty much when I got to go so I kept it as quiet as possible,” he said.
When he did break the news to his celebrity parents Ronan Keating and TV presenter Yvonne Connolly, their reaction was a mixture of “nerves and excitement.”
“This is my first real taste of doing a TV reality show and they didn’t know how I was going to react to the whole situation.
"But everyone, my dad and my mum, were buzzing for me once I got it,” he said.
“It was a crazy, crazy couple of days. We had four full days there and it was literally non-stop. I had the best time ever.
"Obviously I didn’t find any romantic relationships but friendship-wise, with the girls and the guys, we will probably be mates for life. It was a crazy, crazy time. It was unbelievable.”
As for which islanders he felt he had a connection with, he cited Welsh paramedic Paige Thorne and said she has invited him out for a night in Swansea when she gets out.
“Me and Paige got on very, very well. While I was in there, we got on so well, she’s such a nice girl and so easy to chat to. But that obviously didn’t make it onto the show, which I was a little surprised by, I can’t lie,” he said.
Jack, who lives in London with his dad Ronan, said that he and some of his fellow Islanders went out in the UK capital last night where he got his first taste of celebrity life.
"From not doing the show to going out there for three weeks to coming back, it’s been a whole different world. It’s been crazy trying to get used to everything,” he said.
Asked who was his favourite couple to win the show, he has tipped Davide and Ekin-Su.
“I think the two of them are going to go the longest for sure,” he said.
Jack said that he was “very grateful” for everything that has happened and “life has changed big-time for me.”