The 56-year-old singer has Jemma, 24, Zac, 23, and nine-year-old Molly his wife Angela Malloch - to whom he tied the knot in 2008 after a decade-long relationship.
And while he is unsure of any specific plans, is hopeful that grandchildren will arrive in the not-too-distant future.
Speaking on UK TV show Lorraine, he explained: "We're still strong together and that's another success story. She was a stage manager, it was 1998 and the rest is really, sort of, history.
"Three kids later ... I don't have grandchildren yet but I'm on the precipice, maybe, I don't know. My oldest is 24 so ... she's lovely. And my 23 year old...I don't know, you never know, Anything can happen!"
Meanwhile, the Too Many Broken Hearts hitmaker - who shot to fame on the Aussie soap opera Neighbours and then released a string of hit records alongside his contemporaries like Kylie Minogue - has also carved out a successful career in musical theatre and is currently touring in The Rocky Horror Show but has been on a health kick in recent times in order to keep following his passion.
He said:" It is about working hard, following your craft and your passion. I've been very lucky, I think you create your own luck, to a certain degree, in life. But timing is everything, I like to keep physically fit and I've changed my diet recently, a lot. Not as many processed foods, I've cut out coffee and I [drink] a lot more water.
"But I'm in my mid-fifties. Wow, how did that happen? That's crazy but we're still here doing it!"
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