Olivia Newton John, who starred with John Travolta in the 1978 hit movie Grease, is in Wales to trace her roots.
Newton-John, 59, is following in the trail of fellow 70s pop singer Donny Osmond who has famously traced his family links back to Merthyr Tydfil.
Most regard her as Australian, but the singer was born in England, and her grandfather ran a pub near Cardiff's modern-day Millennium Stadium.
She and older sister Rona are visiting Wales, filming a programme for the BBC.
They will feature in the BBC show Coming Home which traces the family trees of celebrities.
Newton-John and her sister were taken to film outside the pub in Cardiff where her father, Brinley Newton-John, was born.
In those days it was the New Market Tavern, but now it is part of the O'Neill's pub chain.
The star admitted:"I had no idea our father was born above a pub or that my grandmother Daisy worked behind the bar!
"I'm having a fantastic time - it's been one surprise after another".
Newton-John, who now lives in California, emigrated with her family from England when she was just five.
Her headmaster father, who was also a gifted opera singer and an MI5 officer during World War II, was offered a job at a college in New South Wales, Australia.
Her parents later divorced and the singer went on to carve herself a successful solo singing career in the 1970s, evening coming fourth as Britain's entry in the 1974 Eurovision singing contest.
Then she landed the role of Sandy in Grease about American high school life in the 1950s, famously singing You're The One That I Want to co-star John Travolta.
Olivia Newton-John and John Travolta in Grease in 1978
In the 1990s she fought a battle with breast cancer before returning to the stage and later offered her support to fellow Australian star Kylie Minogue in her recent fight with the disease.
Her visit to Cardiff to trace her ancestors also had another surprise in store when she discovered the current manager of the pub where her father grew up is a distant relative.
Paul Thomas, 33, is her fourth cousin and was delighted to get the opportunity to meet her in person.
"Olivia was lovely - very genuine and down to earth," he said.
"You hear so much about diva antics in the entertainment industry but she was nothing like that at all."