This has nothing to do with what's politically correct, or the definition of mental health. For most men,the most erotic parts of the body are the female face, breasts, buttocks, and legs. For most women, the preferred body parts are the male chest and shoulders, arms, buttocks, and face. Caressing a member of the opposite sex, seeing him or her naked, dancing, intimate conversation, subdued lighting, and music are common arousing situations. Many people crave nonstandard objects and situations.
Common ones are feet, hair, ears, the belly button.
There are others, but forget for the moment the bizarreness of the object. When the panties or the pain become more important than your partner, you have crossed a line. Most people who feel they are male adopt male sex roles, and most females adopt female roles. But we know of the separate existence of sex roles by the non-uncommon dissociations of identity and role. And as accidents of socialization, they can be changed simply by altering the way we raise our children or by some other act of will.