Taboo refers to practices that are generally prohibited because of religious or social pressures. Our English word taboo comes from "tabu" which means "forbidden" in Polynesian. This discussion is confined to sexual taboos, which are sexual practices that have been prohibited because of their perceived negative or harmful effects on society.

Some sexual behaviors have been taboo throughout history and remain so today. These include behaviors such as incest and rape, as well as many paraphilias such as pedophilia (sexual abuse of children by unrelated adults), necrophilia (sexual arousal from viewing or having sex with a corpse), and bestiality (sexual relations with an animal).

Other sexual behaviors that were once taboo no longer are, even though they may not be as approved as some other behaviors that have been accepted as "natural" or "normal".

Taboo Sexual Behaviors
Included in this category are masturbation, oral and anal sex, homosexuality, some forms of bondage, and sex with a menstruating woman. This change can in part be attributed to societies' gradual acceptance of what constitutes normal and harmless sexual experiences between consenting adults.

Incest
Incest is a behavior that is considered taboo and illegal in nearly all societies. Incest refers to any kind of sexual contact (oral, anal, or vaginal sex, fondling, or masturbation) between members of the same family. Definitions of what constitutes a family member vary, but ordinarily they include not only parents and siblings, but grandparents, uncles and aunts, nieces and nephews, step kin, and in most cases, first cousins.

The incest taboo is thought to protect families and society from the negative effects of inbreeding, once common among European royalty and in some other societies.

Masturbation
Masturbation has historically been a taboo, but is now viewed as normal by nearly all medical authorities and social scientists. Even the majority of people in our society now understand masturbation to be a common sexual behavior that is not harmful.

A number of studies in the last several years indicate that attitudes toward masturbation have relaxed considerably compared to earlier times.

Even with this increasing acceptance of masturbation as a natural experience of human sexuality, it is not uncommon for people of all ages to have concerns, questions and guilt over their self-pleasuring experiences. The idea of one pleasuring him- or herself through some form of direct physical stimulation has been the source of great controversy for many generations.

Some religions have referred to this sexual taboo as an "unnatural act" because it had no reproductive goal. Others have focused more on proper sex being the union of the body and spirit of a married couple.

Though the Bible has no clear-cut prohibitions against this sexual activity, both traditional Judaism and Christianity generally regard masturbation as sinful. The Catholic Church in the Vatican paper "Declaration on Sexual Ethics" (December 29, 1975) noted that "masturbation is an intrinsically and seriously disordered act." Thus, masturbation has been described as "self-abuse," "defilement of the flesh," and "self-pollution."

Menstruation
Although menstruation is a normal part of the female reproductive cycle, it is the subject of considerable misunderstanding as a taboo.

Menstruation is the sloughing off of the uterine lining that builds up during the previous month. It occurs about once a month in most women between the ages of approximately 12 and 48.

In ancient times, a menstruating woman was regarded as unclean and liable to pollute foods she handled, or cause crops to wither. The primary reason for this taboo seems to be the fear of blood.

It is thought that menstrual taboos were enforced by men who connected a woman's monthly cycle with the turning of the tides, the changing of the seasons and other events that were mysterious to them.

Superstition and taboos around a woman's monthly cycle continue to persist in our contemporary society.

A common superstition in western culture is the belief that walking under a ladder will bring you bad luck. This myth supposedly evolved from earlier times when people would not walk under a bridge in case a menstruating woman was nearby because they feared her blood would fall on their head.

The belief that the normal process of menstruation is somehow dirty or evil is still evident in the slang expressions of a woman having the "curse" or being "on the rag". It is often seen by men and women as a physical or emotional handicap that makes women "inferior" to men, and many couples view intercourse during menstruation as messy and sloppy and avoid intimate activities for hygienic reasons, although this is not medically necessary.

Bestiality and Necrophilia
Both are strong sexual taboos and forbidden by all major religions. They are considered illegal in the United States and almost everywhere else in the world.

Historically, the primary reason for opposition to these behaviors was related to the fact that they were not procreative acts.

Furthermore, sexual relations between humans and animals or corpses violated the notion that proper sex was to take place between a married couple.

In more modern times society has found both of these practices abhorrent because of the fear of spreading diseases, and because in neither case does someone wishing to practice these illegal social taboos have the willing permission of their sexual partner.