The Westermarck effect: lack of desire for childhood friends

Why are we not sexually attracted to people we knew as children?

Many people are interested in knowing what characteristics and behavioral styles enhance personal attractiveness, but fewer are also trying to find out about the factors that kill any possibility of attraction in the bud.

That is why it is not surprising that so little is known about the Westermarck effecta hypothetical psychological phenomenon according to which human beings are predisposed not to feel sexual desire towards the people with whom we have a continuous relationship during our early childhood, regardless of whether they are related or not.

Why might this curious tendency occur? The explanatory proposals that many researchers are considering to solve the unknown of the Westermarck effect have to do with the phenomenon of incest. incest.

Incest, a universal taboo

In all societies today, there are taboos taboosthat is to say, behaviors and ideas that are not socially accepted for reasons that have to do, at least in part, with the dominant moral or religious beliefs associated with that culture. or religious beliefs associated with that culture. Some of these taboos, such as intentional homicide or cannibalism, are easily inconvenient from a pragmatic point of view, because if they become generalized, they could destabilize the social order and produce an escalation of violence, among other things.

However, there is a universal taboo that we can find in practically all cultures throughout history but whose prohibition is difficult to justify rationally: incest. incest.

With this in mind, many researchers have wondered about the origin of the omnipresent rejection that generates everything related to relationships between family members.. Among all the hypotheses, there is one that has gained strength in recent decades and which is based on a psychological effect based on the combination of genetic innatism and learned behaviors. This is the Westermarck effect hypothesis.

A matter of probabilities

Edvard Alexander Westermarck was a Finnish anthropologist born in the mid-19th century known for his theories about marriage, exogamy and incest. With respect to the latter, Westermarck proposed the idea that the avoidance of incest is the product of natural selection. For him, the avoidance of reproduction between relatives would be part of an adaptive mechanism that we carry in our genes and that would have spread among the population due to the advantageous nature of this behavior in evolutionary terms.

Since the offspring of incest can have serious health problems, selection would have carved into our genetics a mechanism to make us averse to it, which would itself be an adaptive advantage.

In short, Westermarck believed that natural selection has shaped the sexual tendencies of our entire species by preventing relationships between close relatives.

Suppressing sexual attraction to prevent incest.

But how would natural selection promote incest-avoidance behaviors? Ultimately, there is no trait by which we can recognize brothers and sisters at a glance. According to Westermarck, evolution has decided to use statistics to create an aversion mechanism between relatives. Since people who see each other on a daily basis during the first years of life and belong to the same environment are very likely to be related, the criterion that serves to suppress sexual attraction is the existence or not of proximity during childhood.

This predisposition not to feel attraction for the people with whom we come in contact periodically during the first moments of our life would be of genetic basis and would suppose an evolutionary advantage; but, as a consequence of this, we would not have sexual interest for the old ones either, but, as a consequence of this, we would not have sexual interest in old childhood friendships either..

The anti-Oedipus

To better understand the mechanism through which the Westermarck effect is articulated, it is useful to compare this hypothesis with the ideas on incest proposed by Sigmund Freud.

Freud identified the incest taboo as a social mechanism to repress sexual desire toward close relatives and thus make possible the "normal" functioning of society. The Oedipus complex would be, according to him, the way in which the subconscious fits this blow directed against the sexual inclinations of the individual.It follows that the only thing that makes the practice of incest widespread is the existence of the taboo and the punishments associated with it.

The biologicist conception of the Westermarck effect, however, goes directly against what is proposed in the Oedipus Complexbecause in his explanation of the facts, the taboo is not the cause of sexual rejection, but the consequence. This is what makes some evolutionary psychologists hold the idea that it is evolution, rather than culture, that speaks through our mouths when we express our opinion about incest.

Some studies on the Westermarck effect

The proposal of the Westermarck effect is very old and has been buried by a barrage of criticism from anthropologists and psychologists who defend the important role of learned behaviors and cultural dynamics in sexuality. However, little by little it has been gaining ground and has accumulated quite a lot of evidence in its favor.

When people talk about the evidence that reinforces Westermarck's hypothesis, the first case that is usually mentioned is that of J. Sheper and his study on the resident populations of kibbutz (communes based on the socialist tradition) in Israel, where many unrelated girls and boys are raised together. Despite the fact that contacts between these children are constant and extend into adulthood, Sheper concluded that these people rarely have sexual relations with each other. at some point in their lives, being much more likely to end up marrying others.

Other interesting examples

Since Sheper's article was published, there has been criticism of the methodology used to measure sexual attraction without cultural or sociological factors interfering, and yet many other studies have been published that reinforce the Westermarck effect hypothesis.

For example, research based on past questioning of the Moroccan population showed that having a close and continuous relationship with someone during early childhood (regardless of whether he or she is related or not) makes it much more likely that when you reach adulthood you will feel aversion to the idea of marrying this person.

Lack of attraction present even in 'Westermarck marriages'.

In addition, in cases where two people who have grown up together without sharing Blood ties marry (e.g., by adult imposition), they tend not to leave offspring, perhaps due to lack of attraction, tend not to leave offspring, perhaps due to a lack of attraction between them.. This has been found in Taiwan, where there has traditionally been a custom among some families to let the bride be raised in the house of the future husband (marriage Shim-pua).

The taboo is linked to continued cohabitation.

Evolutionary psychologist Debra Lieberman also helped bolster the Westermarck effect hypothesis through a study in which she asked a number of people to fill out a questionnaire. This form contained questions about their family, and also presented a series of reprehensible actions such as drug use or homicide. The volunteers had to rank them according to the degree to which they found them wrong, from most to least morally reprehensible, so that they were placed in a sort of ranking.

In his analysis of the data obtained, Lieberman found that the amount of time spent with a brother or sister during childhood was positively correlated with the degree to which incest was condemned.. In fact, the extent to which a person would condemn incest could be predicted just by looking at the degree of exposure to a sibling in childhood. Neither the attitude of the parents nor their degree of kinship with the brother or sister (adoptions were also taken into account) significantly affected the intensity of the rejection of this practice.

Many doubts to be resolved

We still know very little about the Westermarck effect. It is not known, first of all, whether it is a propensity that exists in all societies on the planet, and whether or not it is based on the existence of a partially genetic trait. Of course, it is also not known which genes might be involved, It is also not known which genes might be involved in its functioning.oand whether it manifests itself differently in men and women.

Answers about the psychological and universal propensities typical of our species, as always, are a long time coming. Only decades of continued research can bring to light these innate predispositions, buried in our bodies under thousands of years of adaptation to the environment.

Bibliographical references:

• Bergelson, V. (2013). Vice is Nice But Incest is Best: The Problem of a Moral Taboo. Criminal Law and Philosophy, 7(1), pp. 43 - 59.

• Bittles, A. H. (1983). The intensity of human inbreeding depression. Behavioral and Brain Sciences, 6(1), pp. 103 - 104.

• Bratt, C. S. (1984). Incest Statutes and the Fundamental Right of Marriage: Is Oedipus Free to Marry?. Family Law Quarterly, 18, pp. 257 - 309.

• Lieberman, D., Tooby, J. y Cosmides, L. (2003). Does morality have a biological basis? An empirical test of the factors governing moral sentiments relating to incest. Proceedings of the Royal Society of London: Biological Sciences, 270(1517), pp. 819 - 826.

• Shepher, J. (1971). Mate selection among second generation kibbutz adolescents and adults: incest avoidance and negative imprinting. Archives of Sexual Behavior, 1, pp. 293 - 307.

• Spiro, M. E. (1958). Children of the Kibbutz. Cambridge: Harvard University Press. Citado en Antfolk, J., Karlsson, Bäckström, M. y Santtila, P. (2012). Disgust elicited by third-party incest: the roles of biological relatedness, co-residence, and family relationship. Evolution and Human Behavior, 33(3), pp. 217 - 223.

• Talmon, Y. (1964). Mate selection on collective settlements. American Sociological Review, 29(4), pp. 491 - 508.

• Walter, A. (1997). The evolutionary psychology of mate selection in Morocco. Human Nature, 8(2), pp. 113 - 137.

• Westermarck, E. (1891). The history of human marriage. Londres: Macmillan. Citado en Antfolk, J., Karlsson, Bäckström, M. y Santtila, P. (2012). Disgust elicited by third-party incest: the roles of biological relatedness, co-residence, and family relationship. Evolution and Human Behavior, 33(3), pp. 217 - 223.

• Wolf, A. (1970). Childhood Association and Sexual Attraction: A Further Test of the Westermarck Hypothesis. American Anthropologist, 72(3), pp. 503 -515.