Incest is the participation in sexual activity with, or marriage to, a close family member. Not only is this activity generally considered taboo and immoral, it is usually a criminal offence. Marriage and sexual behaviors are generally treated with the same consequences.
The place where the cultural differentiation occurs is in the definition of ‘close family member’. Some jurisdictions consider only those related by birth, some those related by adoption or marriage, while others prohibit sexual relations between people who grew up in the same households. In Western society the normal forbidden relationship line is drawn at first cousins, while anything further away is tacitly accepted.
In terms of slang or common usage, ‘incestuous’ can also refer to relationships in tight knit social groups, inappropriate close relationships between an authority figure and a subordinate, or between people in the same profession or creative field.
Incest finds it roots in historical creation mythology, and in social practices of societies all around the world. At the same time incest’s prohibitory social nature arises not only from our religious roots, but, as we will see, a biological imperative.
Many American states recognize two separate degrees of incest, the more serious degree covering the closest blood relationships such as father-daughter, mother-son and brother-sister, with the less-serious charge being pressed against more distantly related individuals who engage in sexual intercourse, usually down to first cousins.
Despite the strong stigma attached to incest, even the more serious charge is generally prosecuted as the least severely-punishable class of felony (in New York state for example, the maximum penalty is four years in prison), and the less serious charge is usually only a misdemeanor. Curiously, many incest laws do not expressly proscribe sexual conduct other than vaginal intercourse (such as oral sex) or, for that matter, any sexual activity between relatives of the same gender - so long as neither party is a minor. This does not mean that the social ostracization that can occur as a result of such activities is not far greater than the punishment of the state.
This lenient legal position is in stark contrast with that in Australia, where incest is punishable by a maximum of 25 years imprisonment for the more serious form of penetrating a child (even if that “child” is over 18), and 5 years for the less serious charge of sexual penetration of a (half) brother or (half) sister.
Incest at its most immoral (according to western moral standards) is most frequently engaged in by parents of both sexes with their children. This is where incest can cross the line between consensual prohibited sex, and abusive pedophilia. A study by Floyd Martinson found that 10-15% of college students have had a childhood sexual experience with a brother or sister.
One of the few widely, but by no means universally, agreed upon lines in the sand is that incest by parents is abuse and should be discouraged. Despite this sentiment some societies still consider incest an inescapable fact of life. In many societies some forms of sexual contact between close family members is socially (and sometimes even publicly) acceptable and even encouraged.
In looking at the motivation behind societal proscriptions against incest, it is important to look more for the general rules and less at the particular situation. Anthropologists studying the "incest taboo" have noticed that incest occurs in most societies, whether or not there is a prohibition against that activity; so the question of why we have societal rules against it in the first place becomes more important.
To more closely examine this question we will look at the three most prominent origin theories, and their counters of the incest taboo.
This theory is based on the observance of congenital birth defects caused by inbreeding. Anthropologists reject this explanation, as inbreeding does not lead to congenital birth defects per se; it leads to an increase in the frequency of homozygotes( in layman’s terms: the passing on of bad genes, magnified because people with similar genetic codes will have similar genetic defects).
Counter to this theory’s reasoning is that homozygote’s can lump potential defects together, effectively reducing the amount of defects in the population, and thus making it beneficial for the species. For example: if children born with this type of heritable birth defect die (or are killed) before they reproduce, the ultimate effect of inbreeding will be to decrease the frequency of defective genes in the population.
Another interesting note worthy of mention is that sexual stimulation has become a passtime; ie. its not just for making kids anymore.
Claude Lévi-Strauss has argued that the incest taboo is in effect a prohibition against same-group relationships (endogamy), and the effect is to encourage relationships outside the group (exogamy). Exogamy promotes the linking of otherwise unrelated households or lineages, thus strengthening social solidarity.
This theory was debated intensely by anthropologists in the 1950s. It appealed to many because it used the study of incest taboos and marriage to answer more fundamental research interests of anthropologists at the time about the mapping of social interactions. One of the primary dissenting opinions regarding this particular theory is about the origins of the social interaction. Since society has many different purposes and definitions around the world, how can the incest taboo be only a result of social bonds, when the taboo exists in places where socialized, cosmopolitan types communities don’t exist?
Finally, there is a lot of belief that the incest taboo finds its origins in Judeo-Christian religious text. The biblical prohibitions against incest are quite pronounced and prolific. They appear in every major mono-theistic text for the last 4000 years. Some have even attempted to use this theory to explain the incest taboo in places where western-monotheistic religions didn’t exist. By looking at the silk trade and other influences of western society upon non-western groups, some experts have argued that this tenet was specifically strong and imprinted itself on other cultures.
This theory gains some legitimacy when used in conjunction with the above theories. If there is a social and biological imperative to avoid incestuous relationships, then any institutionalized and supposedly legitimate prohibition against such acts would be easily accepted.
There seems to be good evidence from experts (Egyptologists and historians on the subject) that suggest incestuous marriages were widespread during some, if not all of Egyptian history. This claim is supported by numerous papyri that recorded families having brother/sister unions. Apparently our cultural acceptance of the incest taboo led to academic skepticism by some, who felt it unlikely that the papyri actually were asserting that such a powerful civilization as Egypt, would have allowed the common violation of this taboo. This doubt in the validity of the records of common incestuous relationships has collapsed completely in the face of the cumulative evidence of scores of papyri.
There does appear to be legitimate doubts as to how long common incest occurred for in Egyptian history. There is evidence to suggest that at least within the royal family there was a tradition of hyper-gamy for men. This is where a king or his son might marry a commoner, but his daughter could not marry beneath herself, without the act be considered degrading. As a result, the royal princess often found herself either marrying her royal brother, or living her life without a spouse. Thus we see that incest may have been more ubiquitous amongst the lower classes or for women, than for higher stationed men. Proximity and lack of choices may in some instances have been the root of these widespread inter-family relationships.
It is common knowledge of the prevalence of incest within royal families, and to some degree this is true. Adult incest within (European specifically) royal dynasties was probably encouraged to concentrate wealth and political influence within the family. This seemed to have worked financially but there is empirical evidence to suggest that at the same time this resulted in abnormally high instances of rare genetic defects and diseases.
Although the marriage unions were often not consensual, with young adults or children forced to marry close relatives, this does not imply the sex was non-consensual. Best known for this practice, which included brother-sister marriages, are some of the dynasties of Ancient Egypt (as suggested above), ancient Hawaii, and the Pre-Columbian Mixtec.
More modern dynasties where there was frequent familial intermarriage were the mid-Habsburgs - one branch ruled over Spain and the other over Austria. The Spanish branch died out in 1700, but the last Spanish Habsburg king, Carlos II had been married to María-Luisa of Orleans, grand-daughter of King Charles I of England and niece to King Louis XIV of France. However, over the last century, Kings Philip II, Philip III, and (for his second time) Philip IV all married their Austrian cousins. The Austrian branch continued to rule until 1918, and they are still alive and prospering today.