Incest:

Incest is sexual intercourse between close relatives that is usually illegal in the jurisdiction where it takes place and/or is conventionally considered a taboo. The term may apply to sexual activities between: individuals of close “blood relationship”; members of the same household; step relatives related by adoption or marriage; and members of the same clan or lineage. See also Laws regarding incest.

Consensual adult incest is seen by some as a victimless crime. Although it is illegal or partially prohibited in most countries, Russia, China, The Netherlands, Spain, France, Turkey, Israel and the Ivory Coast have no legal prohibitions on consensual incest between adults, and Switzerland has considered legalizing it.

The incest taboo is and has been one of the most common of all cultural taboos, both in current nations and many past societies, with legal penalties imposed in some jurisdictions. Most modern societies have legal or social restrictions on closely consanguineous marriages. In some societies, such as that of Ancient Egypt, brother–sister, father–daughter, and mother–son relations were practiced among royalty as a means of perpetuating the royal lineage. In addition, the Balinese and some Inuit tribes have altogether different beliefs about what constitutes illegal and immoral incest.

Terminology:

The English word incest is derived from the Latin incestus, which has a general meaning of “impure, unchaste”. It was introduced into Middle English, both in the generic Latin sense, and in the narrow modern sense. The generic Latin sense preserved throughout the Middle English period. The derived adjective incestuous appears in the 16th century. Prior to the introduction of the Latin term, incest was known in Old English as sibbleger (from sibb ‘kinship’ + leger ‘to lie’) or mǣġhǣmed (from mǣġ ‘kin, parent’ + hǣmed ‘sexual intercourse’) but in time, both words fell out of use.

Prevalence and statistics:

Incest between adults and those under the age of consent is considered a form of child sexual abuse that has been shown to be one of the most extreme forms of childhood abuse, often resulting in serious and long-term psychological trauma, especially in the case of parental incest. Prevalence is difficult to generalize, but research has estimated 10–15% of the general population as having at least one such sexual contact, with less than 2% involving intercourse or attempted intercourse. Among women, research has yielded estimates as high as 20%.

Father-daughter incest was for many years the most commonly reported and studied form of incest. More recently, studies have suggested that sibling incest, particularly older brothers having sexual relations with younger siblings, is the most common form of incest, with some studies finding sibling incest occurring more frequently than other forms of incest. Some studies suggest that adolescent perpetrators of sibling abuse choose younger victims, abuse victims over a lengthier period, use violence more frequently and severely than adult perpetrators, and that sibling abuse has a higher rate of penetrative acts than father or stepfather incest, with father and older brother incest resulting in greater reported distress than stepfather incest.

Between consenting adults:

Sexual activity between adult close relatives may arise from genetic sexual attraction. This form of incest has not been widely reported in the past, but recent evidence has indicated that this behavior does take place, possibly more often than many people realize. Internet chatrooms and topical websites exist that provide support for incestuous couples.

Proponents of incest between consenting adults draw clear boundaries between the behavior of consenting adults and rape, child molestation, and abusive incest. According to one incest participant who was interviewed for an article in The Guardian:

“You can’t help who you fall in love with, it just happens. I fell in love with my sister and I’m not ashamed … I only feel sorry for my mom and dad, I wish they could be happy for us. We love each other. It’s nothing like some old man who tries to fuck his three-year-old, that’s evil and disgusting … Of course we’re consenting, that’s the most important thing. We’re not fucking perverts. What we have is the most beautiful thing in the world.”

The Guardian article also states:

Voices in Action, a US support group for victims of incest, vehemently rejects these arguments: “These teens have been brainwashed into believing this behaviour is natural; it is not … Sexual abuse is learned behaviour.” But some political thinkers are prepared to support the distinction between abuse and consenting relationships.”

In Slate Magazine, William Saletan drew a legal connection between gay sex and incest between consenting adults. As he described in his article, in 2003, U.S. Senator Rick Santorum publicly derided the theory of the Supreme Court ruling to allow private consensual sex in the home (primarily as a matter of Constitutional rights to Privacy and Equal Protection under the Law). He stated: “If the Supreme Court says that you have the right to consensual sex within your home, then you have the right to bigamy, you have the right to polygamy, you have the right to incest, you have the right to adultery.” However, David Smith of the Human Rights Campaign professed outrage that Santorum placed being gay on the same moral and legal level as someone engaging in incest. Saletan argued that, legally and morally, there is essentially no difference between the two, and went on to support incest between consenting adults being covered by a legal right to privacy. UCLA law professor Eugene Volokh has made similar arguments.

Incest defined through marriage:

Some cultures include relatives by marriage in incest prohibitions; these relationships are called affinity rather than consanguinity. For example, the question of the legality and morality of a widower who wished to marry his deceased wife’s sister was the subject of long and fierce debate in the United Kingdom in the 19th century, involving, among others, Matthew Boulton. In medieval Europe, standing as a godparent to a child also created a bond of affinity.[citation needed] But in other societies, a deceased spouse’s sibling was considered the ideal person to marry. The Hebrew Bible forbids a man from marrying his brother’s widow with the exception that, if his brother died childless, the man is instead required to marry his brother’s widow so as to “raise up seed to him” (taken from Deuteronomy 25:5–6).

Laws:

Incest is illegal in many jurisdictions. The exact legal definition of “incest,” including the nature of the relationship between persons, and the types sexual activity, varies by country, and by even individual states or provinces within a country. These laws can also extend to marriage between subject individuals.

In some places, incest is illegal, regardless of the ages of the two partners. In other places, incestuous relationships between two consenting adults (with the age varying by location) are permitted. Such countries where it is permissible and legal, includes the Netherlands and Sweden where incestuous couples must seek government counseling before marriage. The only type of incestuous relationship allowed by law in Sweden is that between half-siblings.

A jurisdiction’s definition of an incestuous relationship will also limit who a person is permitted to marry. Some jurisdictions forbid first-cousins to marry, while others limit the prohibition to brothers, sisters, mothers, fathers, aunts and uncles.