In sexual deviation, sexual satisfaction requires manipulation of material objects or abnormal sexual behavior.  Usually, such behavior harms others or takes the place of normal sexual activity.  Sexual deviation is more common in men than in women. However, this is not implying that women do not interact in the same deviances.  Prognosis varies with the kind of deviation and with the person's motivation to change their behavior.

The causes of sexual deviation are thought to include a combination of sociocultural, physical , and psychological factors, for example, an overly intimate relationship with parents, or rejection, hostile treatment, and social deprivation during childhood, all of which diminish self-esteem.  They provoke feelings of inadequacy or hostility expressed through sexually deviant behavior.  Most sexual deviants are outwardly quiet and reserved.  Their poor self-image, low frustration level, and overwhelming feelings of fear and inadequacy prevent them from experiencing normal relationships and effective interactions with others.

Types of Sexual Deviation

Exhibitionism:  The exhibitionist derives sexual satisfaction from exposing their genitals in public.  While they are not dangerous and do not participate in more serious deviations, their need to reinforce their masculinity in this manner cannot be treated by reassurance alone: psychiatric treatment is necessary.

Voyeurism:  The voyeur obtains sexual satisfaction by watching others engaged in sexual activity or by observing a woman or a man nude or undressing.  Since normal sexual activity may include an element of voyeurism, this is considered a deviation only when it disturbs others or replaces normal sexual activity.  The voyeur only occasionally engages in dangerous sexual deviations.

Fetishism:  The fetishist receives gratification by manipulating a material object, usually an article of women's clothing.  Often this object becomes the sole focus of sexual desire.  It can also be a part of the body used for physical or mental sexual stimulation. The behavior is widespread and can be in many forms such as a benign form like having a preference for their partner to wear a certain piece of lingerie before sex, to a vicious form such as, a rapist cutting off a lock of hair from their victim for later use in masturbation.

Transvestism:  For the transvestite, sexual stimulation is achieved by wearing clothes of the opposite sex, often in public.  Some transvestites are homosexual, but others lead fairly contented married lives and engage in normal sexual activity.  The transvestite is not dangerous to others and seldom seeks treatment.

Rape:  The rapist uses violence to sexually assault a non-consenting partner.  Rape is a violent crime, an expression of hostility, power, and rage, not just sexual gratification.  It may occur as an isolated incident but is more often part of a recurring behavioral pattern.  The rapist needs psychotherapy.  The rapist often has feelings of violence or hatred toward women, or sexual problems, such as impotence or premature ejaculation.  Frequently, they are socially isolated and unable to form warm, loving relationships.  Some rapists seem to be psychopaths who seek pleasure, regardless of how it affects their victims; others rape to satisfy a need for power.  Some have been abused as children.

Necrophilia:  The necrophiliac engages in sexual intercourse with a corpse.  This rare deviation usually involves a murderer and their recently killed victim, and requires psychotherapy.  There are three different types of necrophiliacs: those in which they murder to obtain a corpse, those who use a corpse that is already dead for sexual pleasure and those who only fantasize, envisioning the act but not acting on it.

Pedophilia:  The pedophiliac has sexual relations with children, frequently those of friends or relatives.  The pedophiliac may be homosexual or heterosexual, and also needs psychotherapy.  Pedophiles may also murder their victims afterward in fear that they may be exposed for their vicious acts.

Sadism:  The sadist obtains sexual satisfaction by inflicting physical or mental pain on the sexual partner, is likely to commit murder or other violent crimes, and is dangerous.  Psychiatric treatment is necessary.  Some participate in sadism and masochism as a sexual fantasy.

Masochism:  The masochist achieves sexual gratification through physical or mental abuse before, during, after, or instead of sexual intercourse.  Masochism results from feelings of guilt and the desire to be punished, and calls for psychiatric treatment. 

Incest:  Incest (sexual relations with family members) most often involves a father and his daughter.  The wife/mother may tacitly approve of the activity.  Once begun, incest tends to persist and may extend to include several children.  An incestuous father was often socially deprived during his childhood.  He seldom commits other crimes.  As a rule, all members of an incestuous family need psychiatric treatment.

Diagnosis requires careful interpretation of clinical assessment, including the patient's history and physical examination.  Often a referral from the criminal justice system leads to diagnosis.  Professionals, when dealing with sexual deviants, need to remain non-judgmental, avoid activity requiring close physical contact (if possible), firmly stop all sexual overtures, and avoid reinforcing deviant behavior.  Maintain a safe, non-threatening environment, and set realistic treatment goals.  Sexual deviants may also have other psychiatric disorders and should be treated accordingly.

Source:  Leibrandt, Thomas, Diseases, Causes and Diagnosis, 2001