Jayne Mansfield established a career as a major Hollywood sex symbol during the 1950s and early 1960s, but behind the scenes, she was a “good” mom who “cared so much” about her kids, her youngest son, Tony Cimber, exclusively tells Closer Weekly. When she wasn’t raising her children, the late actress was performing at nightclubs, turning heads as a Playboy Playmate and competing with fellow showbiz sex pot, Marilyn Monroe.

At a party at New York’s Hotel Astor in 1955, two bombshells almost collided. Jayne, the star of the Broadway hit Will Success Spoil Rock Hunter?, stood on one side of the room, while the other famous blonde, film star Marilyn, sat at a table with her back to the younger woman. “Jayne was enamored of Marilyn and wanted to go over, but Marilyn snubbed her,” biographer Frank Ferruccio tells Closer in the magazine’s latest issue, on newsstands now. The insult stung. “For someone who was very sure of herself, it was hard to be snubbed by her idol.”

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Marilyn’s jealousy wasn’t without cause. Though there were many buxom blondes who followed in her footsteps, Jayne’s 40-21-36 figure wasn’t her only asset. She excelled as an actress and nightclub singer; had an IQ of 163; and a genius knack for generating publicity. “She loved being the center of attention,” says Tony, who tells Closer it wasn’t just Jayne’s work that set her apart. “She also cared so much about being a good mother.”

Long before women were told they could have it all, Jayne, who was born Vera Jayne Palmer in Bryn Mawr, Pennsylvania, balanced an enviable career with a robust family life. The three-times wed performer was a mother of five children — including Law & Order: SVU star Mariska Hargitay. “She was just so ahead of her time,” Mariska says. “She was an inspiration, she had this appetite for life.”

Growing up, Jayne wanted to be Shirley Temple. Childhood dance classes led to piano, violin and viola lessons. Along the way, Jayne also learned five languages. “She was multitalented,” says Ferruccio, author of Diamonds to Dust: The Life and Death of Jayne Mansfield and Did Success Spoil Jayne Mansfield?

After Jayne created a sensation on Broadway in 1955, Hollywood came courting. She signed with 20th Century Fox — not coincidentally the same studio where Marilyn was under contract. “Jayne made $2,500 a week, which was double the salary Marilyn was paid when she started,” says Ferruccio. “The studio was purposely pitting Jayne against Marilyn because Marilyn was giving them a hard time and didn’t want to do the dumb blonde roles anymore.”

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Ambitious Jayne didn’t mind playing dumb, although she won a Golden Globe for a dramatic role in 1957’s The Wayward Bus. And unlike Marilyn, she courted publicity and made friends of the press. “Jayne would pose for a picture for anyone, anywhere, at any time,” says Ferruccio. “She was a very driven woman. It was in her blood.”

Her ambition extended into her personal life. Jayne wanted to be the best hands-on mother and took her brood with her everywhere. “She was not a star mom. She was a great mom,” says Ferruccio. “When she toured, she brought them with her as opposed to leaving them with strangers. She wanted to be a part of their lives.” But it was difficult. Jayne’s first husband, Paul Mansfield, sought custody of their daughter Jayne Marie in 1956, using the actress’ appearance in Playboy as evidence that she was an unfit mother.

Career and motherhood seemed to rank higher on Jayne’s list of priorities than the men in her life. “She loved passion, but she got bored very fast,” says Ferruccio, who believes that she enjoyed her happiest union with bodybuilder Mickey Hargitay, her second husband to whom she was wed from 1958 to 1964. “It was one of the greatest experiences of my life to be married to her. She was a great lady,” Mickey once said. “She was entirely different than what people write about her.”

Gossips did write about Jayne — and it wasn’t always nice. One persistent rumor is that she had love affairs with both John F. Kennedy and his brother Robert F. Kennedy. “I believe that rumor was invented by one of her biographers,” says Ferruccio. “Timeline-wise, she would have been pregnant with Mariska, so I dismissed it. I think that was said to make it look like Jayne was trying to do everything Marilyn did.”

But like Marilyn, Jayne also died tragically at a young age. The 34-year-old performer was killed when the car she was riding in rammed into a truck late at night in a dense fog. The three adults in the front seat died instantly, but Jayne’s children Mickey, Zoltan and Mariska sustained only minor injuries. “Jayne’s greatest regret would be not growing old with her children,” says her son Tony. “But I can also tell you that she never really left. She lets her presence be known. And it’s so Jayne.”

Mariska has felt her mother too. “She’s still with me,” the actress says to Closer. “I look at my life now and think, I’m on a TV show, I run a foundation, I run a household, I’m a mom, I’m a wife, I’m a lot of things. I realize I’m like that because it’s what I know.”