EXCLUSIVE: Johnny Carson's 'Cold and Conservative' Mother Left Her Famous Son 'Hurting Badly' — After She Rejected a Controversial Joke

Johnny Carson's mother, Ruth, left her son in pain after a joke she deemed controversial, RadarOnline.com can reveal.

In the new book, Love Johnny Carson: One Obsessive Fan's Journey to Find the Genius Behind the Legend, author Mark Malkoff puts the spotlight on the late-night icon's relationship with his conservative mom.

Just five years into Carson's legendary run as host of The Tonight Show, the funnyman landed on the cover of TIME magazine, and what should have been a proud moment for his family turned into a painful memory for Carson.

Malkoff writes: "... Its opening paragraph hit a sore spot. The profile began in Nebraska, in the home of Ruth. She and the writer were watching Tonight. During his opening monologue, Carson told a joke about 'sex-change operations' that deeply conservative Mrs. Carson didn’t appreciate."

"'That's not so funny, McGee,' Ruth Carson said, referencing one of her son's favorite radio shows from childhood, the NBC sitcom Fibber McGee and Molly. Whenever the husband made a bad joke, his wife, Molly, would respond with what became a popular catchphrase, 'T'ain’t funny, McGee!'"

Malkoff adds that while Ruth "criticized that one particular joke, her comment perpetuated the myth that Johnny's mother didn't find her son funny. It never occurred to her that TIME would highlight her offhand comment. It didn't matter that Ruth often praised Johnny's comedy to other journalists and stayed up nightly to watch his show.

"Johnny was devastated that his mother's criticism of him would be read by millions. (Carson's wife) Joanne said, 'It really hurt him badly.'

"I'm unaware if Johnny and his mother ever discussed it, but confrontation with anyone, even his family, was rare for the host and avoided at all costs."

"There were great troubles... She was just cold, difficult, and forbidding," Tonight staffer Emily Marshall told Malkoff. "She wasn't a loving mother, and I think he never got over it."

Meanwhile, according to Carson staffer Myra Paikin Richman, when the comedian's parents attended one taping of the show in New York City, Richman recalled, "I remember feeling sad for Johnny when I met his mother. She was cold."

Malkoff writes even Carson's wife attempted to keep the TV star away from his mom, telling her husband, "I would appreciate having as little contact with your mother as possible."

In response, Johnny is believed to have said, "I know exactly what you mean. Unfortunately, I'm her son, and she doesn't let go." Carson's stage manager, Kevin Quinn, also told Malkoff that Ruth "was very strong, and that's who he revered."

Ruth died in 1985 at the age of 84. However, Carson did not attend her funeral.

In Burt Reynolds' 2015 memoir, But Enough About Me, the actor claimed that Carson would talk to him about his broken relationship with his mother.