Jackie, Tito, Jermaine and Marlon told listeners about their 50-year music career, including details about their first trip to the UK.
They said: "We were on the plane, and we were told we had about 8,000 screaming fans at the airport waiting for us.
"It was chaotic, pandemonium. We didn’t quite expect it, to see fans in sleeping bags waiting for us."
Tito has also released a solo record, entitled Tito Time. He told Sam about how his pop legend brother had inspired him to finish the record.
He said: "After fifty years, I finally decided to do a solo record. I’d been busy being married, and having children, and raising sons and stuff.
"Michael had heard the songs and encouraged me to continue to record. But then right in the middle of it, he passed away.
"I laid off it for two or three years, and then I remembered what he’d said, and it encouraged me to continue."
The group revealed how they "cherish" the memory of their brother, saying they felt "his spirit" whenever they performed.
The group have a busy summer coming up - they're due for several performances, notably at Glastonbury and Love Supreme Festival in July.