Not sure, but I think it appears 'odd' because it is a little girl in a somewhat adult woman pose, she has been 'done up' ie hair to look more adult, so her body shape seems odd because she isn't a woman but a little girl, if that makes sense?
Her head/hair style looks grown up so you are expecting to see a womans body below and it obviously isn't.
I think pictures of child models quite probably are digitally enhanced though.