It was devastating to learn that Santa Claus didn't exist and that babies didn't come from the same dude who peddled pickles, but finding out that the great Johnny Carson, the smoothest guy on my TV set, wasn't as debonair in his personal life?

Childhood is officially over.

It's always heartbreaking to discover that your heroes are fallible creatures, which may be reason enough to avoid watching the latest "Johnny Carson: King of Late Night," an "American Masters" production airing on PBS Monday, 50 years after Carson took over NBC's "The Tonight Show" and 20 years after his retirement.

While this thorough, two-hour documentary is packed with praise -- nearly 50 interviewees pay their respects -- one theme might rattle die-hard fans: Johnny had mommy issues.

"For his entire life, he tried to get her approval and her love and she withheld it, no matter what he did," writer and co-director Peter Jones said in an interview earlier this year, referring to Carson's mother, Ruth.

In the movie's most devastating anecdote, we learn that a Time correspondent doing a cover story on Carson in 1965 watched the opening monologue with Johnny's mother in her living room. After it was done, she stood up and said, "That wasn't funny," and walked into the kitchen.

No wonder the late-night host got divorced three times.

"His whole life, his relationship with women, was really defined by that principal relationship with his mother," Jones said. "None of the marriages ever worked and it was one of his deepest regrets."

Jones, who has done documentaries on Bette Davis and Gloria Swanson, spent 15 years trying to get Carson's cooperation, sending him an annual letter until his death in 2005. In 2002, Carson actually picked up the phone and called.

"He said, 'Peter, it's Johnny Carson. I want to tell you, you write a damn fine letter, but I'm not going to participate in anything on my life because, you know what? I don't give a [expletive],'" Jones said.

With all due respect, I've got to disagree with Carson.

A life this influential demands examination, something his family finally acknowledged by granting Jones unprecedented access to Carson's archives.

A generation that didn't grow up on Carson should know more about the roots of Jay Leno's lengthy monologue, the way Bill Maher punctuates a joke, Jimmy Fallon's silly skits, David Letterman's banter with Paul Shaffer. All have Carson's fingerprints on them.

Younger people should understand that, before the late-night wars, Americans were united in worshipping one, and only one, talk-show personality.

The fact that so many top names agreed to interviews, including Leno, Angie Dickinson, Don Rickles and Conan O'Brien, is a testimony to Carson's greatness. Even the press-shy Letterman sits for a chat (although he doesn't say anything terribly revealing). Joan Rivers, the fill-in host who was banished from the show and Carson's life after she jumped to Fox to launch her own short-lived program, admits for perhaps the first time that she should have gotten her mentor's blessing before becoming his competitor.

Carson may be grimacing from his grave, but I can only hope he's also laughing right along with us as we look back at Aunt Blabby, Carnac the Magnificent and the smoothest cat in the history of late-night TV.

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