Sir Elton John "never thought" he'd have children.

Sir Elton John and David Furnish

Sir Elton John and David Furnish

The 68-year-old singer and his husband David Furnish are parents to five-year-old Zachary and three-year-old Elijah - who were born via a surrogate - and the 'Your Song' hitmaker can't believe how much they have changed his life.

He said: "If you'd had said to me 10 years ago I'd be sitting on your show married to the man I love and have two beautiful children I would have said you put acid in my drink.

"But life throws you challenges and life throws you curve balls and great curve balls and these two children have come along at a time I never thought I'd have children.

"They are the greatest thing in our lives. There's no words to describe how much we love these boys. They're just amazing."

The two boys are already developing an interest in music, though Elton is unsure of their tastes.

He said: "I mean they love 'Hotline Bling' that's their favorite song. And they love 'Uptown Funk' and Zachary likes Kraftwerk, which is a bit worrying."

But the youngsters also enjoy their famous father's biggest hits.

Elton added in an interview with Ellen DeGeneres: "They sing 'Rocket Man', 'Don't Go Breaking My Heart' and 'Bennie and the Jets'."