Among humans, there exists a universal taboo against incest. It is hard to describe incest, as it is hard to put a bead on what it is about incest that we, as humans, dislike. The existence of the taboo stems from many properties of incest that instil fear in humans. Although the rules and views on incest vary between cultures, incest is prohibited in probably every human culture. We can infer from this that the avoidance of incest is embedded into human nature. So natural is the avoidance of incest, in fact, that we see similar traits in our closest primate relatives from the animal kingdom. With further examination of these observations, we can attempt to derive a definition of incest in human culture.
For most of us, incest strikes us as being something wrong, or even evil. Mere words seem to fall short in trying to describe incest. For many, the feeling which is associated with incest lies somewhere between a feeling of being queasy and sickened, and a fear of an evil horror. Although numerous situations can constitute incest (father-daughter, sister-brother, cousin-cousin, etc.), it can fall into two general classes, each somewhat resembling other sexual crimes in a different way. The first is an involuntary incest behaviour typically between an adult and a child, such as that between father and daughter, or uncle and niece. This is along the same lines as rape, which is very obviously wrong. The other type of incest is voluntary, such as that between brother and sister, or between cousins - and can so be compared with another immoral sexual behaviour - adultery. While incest can be seen to resemble rape and adultery, rape and adultery can not be paralleled with incest - it doesn’t go both ways. On top of the evil and ‘wrongness’ of incest, there seems to be an additional component of unnaturalness. We can see from this that coming to terms with a definition of incest is a difficult task. At this point, we can only see that it is wrong and assume it is unnatural.
This confusion as to what incest is and how we feel about it, among other things, are contributing factors in humans having a taboo on incest. Humans generally seem to have taboos on things for a variety of reasons which make us afraid of that particular thing. First, many (humans in general) have taboos on things that they don’t understand. This can be typified by racist, anti-gay, and other intolerant attitudes which are common amongst humans. Second, we tend to have taboos on things which are unanimously regarded as being morally wrong. This is perhaps the most obvious reason to prohibit an activity, and explains laws against murder, stealing, and many other deeds which are universally regarded as being wrong. Third, there is a taboo on dangerous actions, such as playing with matches (children), and hitting from behind in sports. Less obviously, we have taboos on things that make us feel uncomfortable. This is typified by codes which prohibit unsanitary people, and laws against indecent exposure, or explicit content. The act of incest possesses all of these qualities; it inarguably causes an uncomfortable feeling at the mere thought or visualisation of the act, is dangerous to the species in the way that it can spawn birth defects, is definitely misunderstood (I, for one, certainly do not understand it), and is generally perceived as being wrong or immoral. Incest possess all of the aforementioned ‘taboo properties,’ making it not only tabooed, but one of the most feared issues in society, and consequentially perhaps the ‘mother’ of all human taboos.
So then, since incest is a such a very scary and unnatural thing, one would think that humans would have a strong tendency to avoid it. This is, as Edward Westermarck would attest to in his essay: “The Horror of Incest,” the case in all human cultures. It is certainly true that incest does occur, (for if it didn’t, there would be no such term) on occasion. However, as Westermarck assures us, this is the exception to the rule, and regarded as abnormality. Different customs do apply in different lands though. Westermarck states that parent-child incest is, in almost every case, frowned upon. Also, brother-sister incest in which the brother and sister are children of the same parents is tabooed in most cases. Westermarck provides numerous examples of this taboo seen in modern society as well as in ancient times. It is seen in what Westermarck would call “savage” (tribal, or clan-based) society, as well as in “civilised” society (like our own i.e. not tribal). In China, incest with immediate family, such as a brother or sister, as well as incest with non-immediate family, such as a grand-uncle, or father’s first cousin, is punishable by death. Even marrying someone with the same surname is punishable by sixty blows. In ancient times, the so-called Aryan people perceived sexual intercourse with one’s mother or daughter or daughter-in law to be a crime serious enough to be punishable by burning. These examples of incestuous behaviour are based on kinship. Many peoples, tribal and otherwise, have a rule of ‘exogamy’ which depends on close living rather than family kinship. In this system, all the members of a horde or village are forbidden to intermarry - depending on familiarity rather than kinship. Lines of descent and last name, play the crucial role in incest law in many cultures. We can see from this that what may be viewed as incest in one culture may not be viewed as incest in another, while some forms of incest are universally considered as such.
Many different rules exist concerning the marriage of two people with the same last name, complicating the notion of incest even further. These different rules have to do with whether the ancestor’s surnames in the particular culture are patrilineal (based on the father’s surname), or matrilineal (based on the mother’s surname). Often, an ‘offence’ is deemed as being incestuous on only one side of the equation . Most cultures that we are familiar with, including the very well-known European culture, are patrilineal. This means that any incest laws restricting marriage between people with the same family name are based on the father’s ancestors. In this case, it may be considered incest to marry or have sexual relations with a fifth cousin, related by marriage only, on the father’s side, and not considered incest to have sexual relations with our aunt on our mother’s side. This may or may not always be true, and is an extreme case, but the point remains that the concept of incest can be seen to be less influenced by biological blood ties than by spelling and phonetics! Clearly, both name and blood relation can have influence wether or not something qualifies as being incest. In addition to this, we must add the factor of close living together - familiarity. This accounts for adopted children situations and step-parent step-child incest occurrences.
The universal human avoidance of incest seems to arise naturally, since it can be observed that it is embedded so deeply in our nature, that we can see it arise in our primate relatives! Chimpanzees, olive baboons, rhesus monkeys, and Japanese macaques rarely mate with close kin. In Jane Goodall’s essay: “Incest Avoidance Among Chimpanzees,” she gives as evidence of this through her observations of chimpanzees. Goodall observed that mating between males and their mothers is extremely rare. In the rare case when a male made sexual advances toward his mother, he is rejected, although most advances from other chimps are accepted. The mothers would go so far as to get their back stomped on rather than submit to sexual intercourse with their son. Only persistent males who manage to chase down or corner their mother succeed in copulating with them, and even then, the mother often runs away before ejaculation. Goodall also observed that chimps tend to avoid sexual relations between brother and sister. The female sibling was seen to mate much less frequently with her brothers, as compared to the amount of times with other chimps. When the male sibling displays a sexual interest in his sister, quite often she turns him down by walking away, resisting, or even attacking him. Even in the exceptional circumstance where a chimp was often seen to mate with her brother, she resisted his advances much more often than she resisted the advances of other chimps. It was seen that chimps avoid incestuous behaviour towards immediate family. No account was made with regards to father-daughter relationships, because only the mother stays with the babies to raise them. Consequentially, neither the chimps nor Goodall has any idea as to who any particular chimp’s father is. Since chimps obviously don’t comply with written laws, their avoidance of incest must be restricted to notions of familiarity or kinship.
So then, we have seen that incest can mean many different things. On one hand, it may depend on where one is are, or where one is from. Further, it may depend on what one’s name is, and how familiar is, or how intimately one knows, the other party. On the other hand, the completely universal taboo against parent-child and sibling incest seems to suggest that incest, ‘in its purest form’, refers to immediate family relations. An attempt at a formal definition from the observations here could be as follows: “Incest is the immoral marriage or sexual intercourse of two parties who are closely related, or are prohibited, by law, to be married.” Unfortunately, language is not always sufficient in describing the real world adequately. As we have seen, it takes a great deal more words than that to attempt to get a feeling, or a complete understanding of the concept of incest.