She's actually the same age as you...
and it's not really her fault - her face is designed in a way that it gives off more a childlike appearance than the more ostensibly "sexy" looks of other models like Alessandra Ambrosio. She doesn't have the sharp edges to her face, she has softer edges, which lends to a more youthful and ethereal look than the more overtly sexy look. I don't really think she contributes all too much to the plastic surgery craze. More people want to look young and sexy rather than just young. (and I mean "young" in the sort of baby-ish look - that's not really a desired look as much as looking like, say, Angelina Jolie is...)