Elton John, David Furnish on '20/20' reveal biological father, Lady Gaga is godmother to baby Zachary

Barbara Walters sits down with Elton John and David Furnish on Friday night's (April 22) episode of "20/20," where they talk about their son Zachary Jackson Levon Furnish-John, including revealing which one of them is the biological father and that Lady Gaga is the baby's godmother.

"When you get to the real person underneath, there's a very simple New York girl who loves her parents," says Elton, of Lady Gaga. "I love her to death and a lot of people say that's crazy, but they don't know her and we do."

The biological father question won't be answered in the preview clips! They do talk about their lives as parents so far, though.

"I knew I'd feel joy but it was the most relaxing thing that's ever happened to me," says Elton. "We change him, we bath him, we feed him and we read him a story every night. And we take him to lunch."

But he assures Barbara that his son will not be a spoiled, silver spoon child of a celebrity.

"The worst thing you can do to a child, and I've seen it happen so many times, is the silver spoon, Being the child of a famous person is very difficult and we're very well aware of the pitfalls of that," says Elton.

"Our life might be very luxurious but it's all come from hard work," adds Furnish. "Both Elton and I have sort of earned everything we've done in our careers and furthered our educations through our own drive and our own ambitions and we want Zachary to be exactly the same sort of way."

Watch the interview in its entirety on Friday night's "20/20," airing at 10 p.m. ET/PT on ABC.

Photo/Video credit: ABC