An everted umbilicus (an 'outie') is a normal anatomical variant that frequently occurs in individuals without any umbilical hernia.
The claim that the umbilicus can evert in the absence of an umbilical hernia is a matter of basic anatomical variation and everyday observation. An 'outie' belly button is simply a normal phenotypic trait distinct from a pathological umbilical defect like a hernia. Therefore, this is common knowledge requiring no formal citation.