Gender dysphoria is like face blindness, a mental illness in which one can not recognize faces. Sufferers of face blindness have to rely on external or cosmetic clues such as someone’s hair or how the dress to identify someone.
Sufferers of gender dysphoria can not recognize gender in themselves or fascinatingly, in other people. They must rely on cues such as length of hair or makeup in order to determine the sex of a person.