Judy Lewis, a psychotherapist and former actress who wrote a book about her complicated heritage as the illegitimate daughter of Hollywood legends Loretta Young and Clark Gable, has died. She was 76.

A longtime resident of Los Angeles, Lewis died of cancer Friday in Gladwyne, Pa., according to her daughter, Maria Tinney Dagit.

Brought up in Bel-Air as Young's adopted daughter, Lewis was an adult when she learned that the glamorous leading lady and Gable, the dashing star of "Gone With the Wind," had conceived her during a brief affair in the 1930s.

Fearful of scandal, Young hid the pregnancy and later fabricated the adoption. Gable never acknowledged that Lewis was his daughter, although he visited her once when she was 15, an experience that Lewis tenderly recounted in her 1994 memoir, "Uncommon Knowledge."

Young was single and 22 and Gable married and 34 when they co-starred in "Call of the Wild" (1935), based on the classic novel by Jack London. The rest of their story unfolds like a B movie: The unmarried, devout Catholic known for playing wholesome roles discovers she is pregnant as she is set to star in legendary director Cecil B. DeMille's religious-themed film "The Crusades," goes abroad to avoid gossip, and returns to Los Angeles to give birth in secrecy. Then she turns the infant over to a home run by nuns, retrieves her daughter before she turns 2, fakes the adoption and raises the child under a cloud of lies.

"I had to write this book," Lewis told The Times in 1994 when her memoir was released. "I don't think anyone knows what it's like not to be acknowledged by your own parents."

She was born on Nov. 6, 1935, in a little house in Venice, where Young hid during the last weeks of the pregnancy. Lewis spent the first months of her life there. According to her memoir, Gable visited her there and was so appalled to find her sleeping in a drawer that he took $400 out of his pocket and told Young to "buy her a decent bed."

When she was eight months old, Young placed her in a Catholic orphanage in San Francisco, retrieving her when she was 19 months old. Her "adoption" was leaked to Hollywood columnist Louella Parsons.

When she was 5, her mother married radio producer Tom Lewis and had two sons with him. Although she had his last name, he never adopted her and treated her poorly. Young apparently never told him that Gable was her daughter's father, but it was an open secret in Hollywood — one that, amazingly, never reached young Judy's ears because all her friends had been instructed not to tell her.

The physical hints, however, were difficult to ignore. Lewis had Gable's broad smile and his famously prominent ears. She hid her ears under bonnets until she was 7, when she underwent surgery to pin them back.

One day in 1950 Lewis came home from Marymount Girls Catholic School to find the screen idol standing in her front hallway.

"I couldn't believe my eyes," she wrote in her memoir. "He was right in front of me, and he was smiling at me. His eyes were crinkled into smile lines at the corners and he was so tall that I had to look up. He was much more handsome than I remembered him from the movies.… What is he doing here? I wondered to myself. But I could say nothing. I was speechless."

She tried to escape upstairs to prepare for a dinner date, but her mother commanded her to stay. Over the next hour, Gable sat beside her on the sofa and engaged her in earnest conversation about herself. Before he left, he thanked her for a lovely visit. Then, she recalled, he "bent down and, cupping my face in his two big hands, kissed me lightly on the forehead."

She never saw him again.

Not until several years later did she begin to grasp the meaning of the mysterious visit. Two weeks before her wedding, she panicked and told her fiance, Joe Tinney, she could not marry him because "I don't know who I am." She said he told her, "Judy, don't worry about it. I know everything about you. You're Clark Gable's daughter." She was astounded.

It took her eight years, when she was 31 and appearing in the soap opera "The Secret Storm," to confront her mother. Young, after throwing up in the bathroom, told her that Gable indeed was her father. Then she made Lewis promise to tell no one.

In the 1980s, after a two-decade acting career that included appearances on Broadway and dozens of television shows, Lewis became a marriage and family therapist, working with foster children and pregnant teens.

Her marriage to Tinney ended in divorce in 1972. In addition to her daughter, she is survived by two grandsons and three half-brothers, including John Clark Gable, who was born after his famous father died of a heart attack while filming "The Misfits" in 1960.

When Lewis' book came out, her mother publicly denied Gable's paternity. Estranged for years, the two women reconciled shortly before Young died in 2000. Young's silence about the affair with Gable was not broken until a few months after her death in "Forever Young," an authorized biography by Joan Wester Anderson.

Lewis never had a chance to ask Gable the questions that swirled in her head for years: Did he want a child? What was he thinking that day they met? Would he have wanted to help raise her if her mother hadn't pushed him away? She said that whenever she watched Gable's loving scenes with his on-screen daughter in "Gone With the Wind," she cried.

"It's very sad to me," she told the London Telegraph in 2002, "because he's so dear with her. I pretend it's me."