Strictly defined, the term incest refers to sexual intercourse between close blood relatives. In broader terms incest is understood to include the sexual exploitation of a child by another person in the family, who serves in a parental role, or in another relationship vested with significant intimacy and authority. The sexual exploitation generally progresses from less intimate contact (i.e., sexual dialogue and unwanted kissing and touching of clothed breasts, buttocks and genitals) to more intrusive contact (i.e. genital fondling and vaginal, anal and/or oral sex). Incest can begin at any age -- even infants can be victims. The abuse usually begins with the perpetrator building trust, bestowing favors, gifts, money, or affection as inducement and then demanding secrecy while violating boundaries. Incest incidences can occur over short or long periods of time. Long-term, repeated abuse is often more traumatic to the victim than a single incident. Rarely is a child capable of putting a stop to incest. Often even telling about the incest is out of the question due to the fear of the possible consequences. Victims desperately desire someone to intervene, terminate the abuse, and protect them from future encounters. Victims may also feel betrayed by other family members who could have intervened and did not.

Incest occurs in all socio-economic groups although it appears to occur with greater frequency in families disrupted by a variety of problems including severe marital conflict, spouse abuse, alcoholism, unemployment and emotional illness. It is reported that more females than males are incestuously exploited although allowing for under reporting, some authorities believe that the percentage of boys abused is the same as among girls. Most reported cases involve a father and a daughter. A rise in disclosures over the last several years is probably explained by changes in public and professional awareness, not increases in true occurrence.

Taboos against incest have been found in virtually all human societies, although some exceptions have been documented, including the Incan society and the societies of ancient Iran and ancient Egypt.

Incest may affect victims in many ways. Individuals may experience a variety of emotional and behavioral symptoms including fear, hostility, guilt, shame, depression, low self-esteem, poor self image, insomnia, sexual behavior disturbances, and/or poor social functioning. Physical signs may include pain or irritation to the genital area, vaginal or penile discharge and difficulty with urination. Long term effects may include depression, prostitution, alcoholism, substance abuse, emotional disorders, learning difficulties, somatization disorders, self-abuse, suicide, sleep disorders, low self-esteem, impaired interpersonal relationships (including lack of trust and revulsion to touch), sexual disturbances, anxiety, post traumatic stress disorder and dissociative disorders.

The severity of these effects is often affected by such factors as the victim's relationship with the abuser(s), the number of abusers, frequency of abuse, and the developmental level of the child at the time of the abuse.

Because incest can have such a profound effect on victims' psychological well-being and ability to form healthy, intimate relationships, treatment by a professional experienced in dealing with trauma and sexual abuse is often recommended. It is important for victims to be able to discuss feelings of confusion, shame, fear, betrayal, and guilt that are commonly associated with incest. It is crucial to reassure anyone who has experienced incest that they are not to blame for causing the abuse and that they did the right thing by telling someone. Of course every effort must be made to protect the child from further abuse and/or retaliation from the abuser for telling. Additionally, professionals are mandated by law (in most states) to report abusive situations in an attempt to legally stop the abuse and hopefully begin treatment and rehabilitation for the abuser.