Biologically speaking, it seems that there is no essential difference between the genders among pac-people. Both Pac-Man and Ms. Pac-Man share an identical body type. It is only markers worn by Ms. Pac-Man that signal the gender difference between the two, her bow and lipstick (well, there is also her mole, which may or may not be painted on a la Marilyn Monroe).
In this regard, Pac-Man and Ms. Pac-Man share something in common with the typical silhouettes that represent the distinction between the men’s restroom and the women’s restroom. These individuals share an identical body type with only the female silhouette differentiated from the unadorned male silhouette by her triangular skirt.