Gilbert Flores/Celebrity Photo
routinely makes World's Most Beautiful lists – including PEOPLE's, in 2005 – but the actress is somewhat bewildered by the widespread interest in her looks.
"Somebody goes, 'Gosh, you're pretty,' " Knightley, 22, tells the U.K.'s Radio Times
. "Thanks. I've got good genes!
But she can't just credit her family, she admits, saying: "OK, I'm on the cover of a magazine but somebody else does the hair, and the makeup, and airbrushes the f--- out of me – it's not me, it's something other people have created."
The Pirates of the Caribbean
star – who replaced Kate Moss
as the face of Chanel's Coco Mademoiselle fragrance – says she also can't understand people's obsession with wanting to be well-known.
"It frightens me when kids go, 'I want to be famous,' " she says. "Why? Because you can get into a restaurant? You know what? If you book [a table], you can get into a restaurant! 'I want to be rich and famous.' Go and work on the stock market."
Knightley's fear about the reaction of "kids" was dealt with in January, when she successfully sued
Britain's Daily Mail
for suggesting she had an eating disorder.
"You couldn't say anything more horrendous," Knightley said of the newspaper's claims about her thin looks – which, she explained at the time
, had to do with the arduous work on the final Pirates
movie. "So yes, I did take a hard line, and I would take that line again."
Knightley is comfortable with herself now, but says in her teens she was too self-conscious to even watch her own rushes, because, she says, "When I was 16, 17, I felt incredibly awkward about the way I looked."