Freckles are associated with being young and given to both children and teens to emphasize their age. It can also be used to brand a younger person as a misfit, perhaps because it's a easily visible mark that other children can make fun of.
Freckles are caused by exposure to sunlight, especially on those with fair skin. The propensity to freckle is determined by genetics. Redheads are genetically [...] [tvtropes.org]