Natalie Portman opens up about surviving child stardom - and how her wild pop star character in Vox Lux relates to her own experience

After nearly 25 years in Hollywood, Natalie Portman has a unique perspective on the dangerous machinations of fame.

It’s a subject central to her new film, Vox Lux, in which the actress, 37, plays a troubled pop icon who survived a childhood trauma that launched her career.

“She is such a wild character, but she’s also someone I felt was a real person, who is the product of this life that has happened to her,” Portman tells PEOPLE in the magazine’s new issue. “You see in this film how a young girl is packaged into this brand, and it’s kind of separate from her. I experienced a different degree of it, in a different way, and obviously I have very different support system than the character in the movie, but you see what the culture wants from you, or demands from you and wants to put out there.”

Natalie Portman in Vox Lux
| Credit: Venice Film Festival

The Oscar winner, who has worked steadily since she made her film debut at age 13 in 1994’s The Professional, knows more than most what that is like. She opened up about the troubling aspects of her early fame at the Women’s March last January, where she revealed that the first piece of fan mail she received was a rape fantasy written by a man.

For much more on Natalie Portman and Vox Lux, pick up the latest issue of PEOPLE.

“I understood very quickly, even as a 13-year-old, that if I were to express myself sexually I would feel unsafe and that men would feel entitled to discuss and objectify my body to my great discomfort,” she said. “I felt the need to cover my body and to inhibit my expression and my work in order to send my own message to the world that I’m someone worth of safety and respect.”

RELATED: Natalie Portman, at 13, experienced ‘sexual terrorism’

Years later, Portman has come to terms with the situation. “I know I was sexualized in the ways that I was photographed or portrayed, and that was not my doing,” she says. “That becomes a part of your public identity.”

Recently, Portman sparked controversy when she said she was “confused” as a teen by a magazine cover on which Jessica Simpson posed in a bikini and said she was a virgin. After Simpson said she felt shamed, Portman apologized and said her comment was aimed at the mixed messages she felt the media was sending, not at Simpson.

Natalie Portman in the 1994 movie The Professional.
| Credit: Everett

Portman says the pressure of being in the spotlight is particularly intense for young women trying to figure out who they are vs. who others want them to be.

“It’s complicated to have your own private development and maturation alongside that [pressure] as a person, kind of having these double identities,” says Portman. “And I think that it’s a big conversation about how many different kinds of things girls and women can be.”

Vox Lux is now playing in theaters.