The 39-year-old catwalk icon landed her first modelling job at the age of 15 years old, but the star doesn't think she would be able to "navigate" the business if she was to forge a career on the runway now.
Speaking to Net-a-Porter's The Edit, the style icon said: "I don't think that I'd be able to navigate [the industry] or do it the way the girls do it today. I don't think it's in my personality.
"I can try, but I'm always going to revert back to being pretty quiet and not wanting to share everything about myself, wanting to connect with people very personally. But I appreciate it; I see how great it is for people and how good people are at it."
And Guinevere doubts her career and regularly questions how she "made it" as a model because she has claimed her "measurements" were "never" what they should have been and she was "strange looking".
She said: "I don't know that I ever should have made it in this business, you know what I mean?
"My measurements were never right, I wasn't commercial and, especially when I started, I was very strange-looking; personality-wise I was a little bit different from girls that are happy in the spotlight. But it's a reality check; I don't walk through the world with people assuming that I'm a model, especially because the type of work that I do isn't in people's faces."
and the star has also revealed she has often been mistaken for "almost everyone" except for the model when she has been on a photoshoot.
She said: "I've had many times where I walk on set and people tell me where I can set up my makeup, or assume that I'm the journalist, the stylist, the hairdresser, the photographer... I get [mistaken for] almost everyone except the model."