"No one believes me when I talk about this, but I'm really maternal," Fox, 23, tells W magazine for its March issue, due on newsstands this week.
But she adds: "I worry that because I've always wanted [kids] so much, as the world goes sometimes, I won't be able to have them, even though I would be able to provide them with such an amazing environment."
The sexy actress also reveals her fears about her fellow females in Hollywood."I don't trust people in this industry, but I especially don't trust girls in this industry, because it's incredibly competitive, and I'm just not interested," she says.
Fox says that she's insecure about her own acting and modeling abilities, despite the success of the Transformers movies and her recent deal to become the new face of Emporio Armani underwear and jeans.
"My main weakness is nerves," she says of her acting. "I have no confidence, and because of that I'm always second-guessing myself."
Of modeling, she adds: "I feel intimidated by fashion. I hate doing photo shoots."
One thing she is pretty confident about: Her sex appeal as an Armani model. "There are some women you could put in underwear and photograph them, and it looks really classy and it doesn't necessarily provoke a pinup image," she says.
"But with me it does, immediately, as soon as I'm in underwear. I'm a Vargas girl," she adds, referring to Alberto Vargas, the famed Peruvian painter of pin-up girls.