Genetic Diversity and Genetic Sexual Attraction

Despite the importance of similarity in genetic sexual attraction, genetic diversity is equally important in love. It appears that both similarities and differences between love partners play important roles.

Evolutionary Value of Genetic Diversity

Genetic sexual attraction plays an important role in triggering love between men and women. However, sexual attraction for sexual reproduction also strives to avoid the negative effect of excessive genetic similarity between loving partners. Inbreeding has a deleterious biological effect on the offspring in terms of health quality, the likelihood of diseases, disabilities, and mortality (see for review, Ceballos et all, 2021; Hasselgren & Norén, 2019).

Therefore, human evolution and population growth throughout history have promoted people to exclude mates with extreme genetic similarity from the pool of possible mating partners. Such mating increases the likelihood of harmful recessive genes and reduces offspring fitness (Ceballos et all, 2021).

Cultural Evolution Encourages Diversity in Genetic Sexual Attraction

Even though consanguineous marriages—mating relations with blood relatives—have been widespread throughout history, cultural norms of incest taboos have evolved in many societies to safeguard against this harmful effect of inbreeding. People likely became aware of the harmful effect of sexual relations between close relatives on the quality of their offspring. Incest, or sex between family members, became a cultural taboo in many societies. Evolving social norms and psychological experiences of love began to respect the principles of biological evolution. They were adjusted accordingly, encouraging the extended reproduction of offspring.

A Controversy over Genetic Sexual Attraction among Family Members

Although people perceive potential mates who resemble their kin as more sexually appealing, incest avoidance evolves from the development of taboos. When awareness of the kin relationship between self and other is bypassed, relatives often look sexually appealing to a person. So, by only consciously acknowledging incest taboos, people suppress their sexual attraction to kin (Fraley & Marks, 2010).

The Benefits of Diversity in Genetic Sexual Attraction Encourage Cultural Taboos against Incest

The difference between partners in their genetics leads to healthier offspring. Therefore, natural selection—and cultural norms accordingly—developed protective psychological mechanisms to decrease the sexual drive for similarity and allow only a suitable measure of variance between partners in love relationships. This evolutionary mechanism might be at the origin of the strong incest taboo among many populations of species and human societies (Lampert 1997, p.14).

Societies in history and modern times have respected the incest taboo, prohibiting sexual relations between females and males who are in kinship relationships. Many human societies have cultural norms prohibiting sexual relations among kin (Lampert, 1997; Murdock, 1949; Westermarck, 1891/1921).

You may also be interested in the articles:


Ceballos, F. C., Gürün, K., Altınışık, N. E., Gemici, H. C., Karamurat, C., Koptekin, D., … & Somel, M. (2021). Human inbreeding has decreased in time through the Holocene. Current Biology31(17), 3925-3934.

Hasselgren, M., & Norén, K. (2019). Inbreeding in natural mammal populations: historical perspectives and future challenges. Mammal Review49(4), 369-383.

Fraley, R. C., & Marks, M. J. (2010). Westermarck, Freud, and the incest taboo: Does familial resemblance activate sexual attraction?. Personality and Social Psychology Bulletin36(9), 1202-1212.

Lampert, A. (1997). The evolution of love. Praeger.

Murdock, G.P. (1949). Social structure. Macmillan.

Westermarck, E. (1921). The history of human marriage (5th ed.). London, UK: Allerton. (Original work published 1891).

Genetic Secrets of Love Attraction

From a biological evolutionary perspective, the genetic similarity must be important for sexual attraction. Intersexual attraction helps sexually dimorphic animals, such as birds and mammals, select a proper mate because they cannot reproduce offspring with anyone. They can do this only with those with whom mating success is possible and higher than with others (Karp et al., 2017; McPherson & Chenoweth, 2012; Owens & Hartley, 1998; Rigby & Kulathinal, 2015).

Do People Fall in Love with Genetically Similar Others?   

For a weird example, a human individual can be attracted by a sexual relationship with a horse, cow, goat, or gorilla. They can even be a nice couple. They may attain sexual pleasure. Nevertheless, such relationships, from an evolutionary point of view, are wasteful expenditures of energy because they are destined to be childless. They are genetically too distant to produce offspring.

However, humans and chimpanzees are more similar in this regard—they have a genetic distance of less than 2%. Therefore, reproductive success in that case could be possible (Lampert 1997).

Therefore, we can expect that genetic factors and corresponding similarities in the physical appearance and chemistry of human individuals can determine their sexual and love attraction. The chemistry of love, which makes some partners more compatible with each other than others, can be real, not metaphorical.

Do we have a genetic predisposition to fall in love with someone?

Optimal Genetic Similarity

In biology, the principle of optimal genetic similarity is important for the evolutionary selection of partners among animals (Lampert 1997). Individuals tend to be attracted to others who are genetically similar to them. However, they prefer to keep their distance from those who are genetically very dissimilar from them. Both factors play their roles in the selection of mating partners with optimal genetic similarity to them.

This principle of genetic similarity may also work among humans. An individual tends to fall in love with a person who, to some extent, is genetically and physically similar. Biological evolution has developed a psychological mechanism that unconsciously attracts individuals to mates who are similar and excludes those who are significantly different. 

Why Are Genetically Similar People Sexually Attractive to Us?

Here is one piece of evidence that such an unconscious attraction is possible (Rushton, 1988). Rushton examined the thousands of court cases in which courts investigated the validity of fatherhood. Genetic testing was used to identify whether a man with whom a woman had sex was actually the father of her baby. Examining those cases, Rushton (1988) was interested in knowing how men and women, at the beginning of their sexual relationship—at the time of conceiving a baby—were genetically similar to each other. The data showed that they were genetically more similar to each other than a random couple. These results indicated that it was likely that potential mates unconsciously recognized their genetic similarity with a partner and, therefore, felt sexual attraction (Rushton, 1988).

Another study used genome-wide SNPs and also supported this genetic similarity explanation of sexual attraction. In a sample of American Whites (non-Hispanic), researchers found that married partners are genetically similar to each other—more than random pairs of individuals (Domingue, Fletcher, Conley, & Boardman, 2014).

The Words of Tentative Limitations

It shall be acknowledged, however, that these findings are descriptive and can be considered tentatively true for a causational explanation. The genetic similarity between partners can be due not only to their genetic assortative mating but also to their shared ancestry (Abdellaoui, Verweij, & Zietsch, 2014). The genetic similarities in couples can be due to genetic population stratification that evolved in a society due to geographical proximity, social homogamy, and ethnic homogamy.

Are Close Relatives More Likely to Fall in Love?

According to the findings presented above, genetically similar relatives in nuclear and extended families perceive each other as physically similar and attractive. Does the genetic similarity of close relatives make them more likely to be attractive and love each other? For example, they can perceive each other as more sexually appealing. Then, the psychoanalytic myths of a boy’s unconscious sexual attraction to his mother (the Oedipus complex) and a girl’s attraction to her father (Electra complex) can be partially true due to their genetic similarity, although the effect of imprinting can also play a role.

Many cases of consanguinity in sexual relationships and marriages have been documented throughout history. In these cases, blood relatives find each other attractive (see Karandashev, 2017, 2022 in press for a review). Consanguineous marriages are still widespread and preferred in many societies in West Asia, the Middle East, and North Africa (e.g., El-Hazmi et al., 1995; Hamamy, 2012). Surprisingly, these cultural traditions have been persistent.

However, the negative impact of incest (sexual intercourse with a child, sibling, grandchild, or parent) on offspring is well documented. Therefore, to safeguard against this harmful effect of incest, cultural norms and incest taboos have evolved in many cultures.

Other Articles of Interest on the Topic:

Genetic diversity and love attraction

Love attraction to familiar others


Abdellaoui, A., Verweij, K. J., & Zietsch, B. P. (2014). No evidence for genetic assortative mating beyond that due to population stratification. Proceedings of the National Academy of Sciences111(40), E4137-E4137.

Domingue, B. W., Fletcher, J., Conley, D., & Boardman, J. D. (2014). Genetic and educational assortative mating among US adults. Proceedings of the National Academy of Sciences111(22), 7996-8000.

El-Hazmi, M. A., Al-Swailem, A. R., Warsy, A. S., Al-Swailem, A. M., Sulaimani, R., & Al-Meshari, A. A. (1995). Consanguinity among the Saudi Arabian population. Journal of medical genetics32(8), 623-626.

Hamamy, H. (2012). Consanguineous marriages. Journal of Community Genetics3(3), 185-192.

Karp, N. A., Mason, J., Beaudet, A. L., Benjamini, Y., Bower, L., Braun, R. E., … & White, J. K. (2017). Prevalence of sexual dimorphism in mammalian phenotypic traits. Nature communications8(1), 1-12.

Lampert, A. (1997). The evolution of love. Praeger.

McPherson, F. J., & Chenoweth, P. J. (2012). Mammalian sexual dimorphism. Animal reproduction science131(3-4), 109-122.

Owens, I. P., & Hartley, I. R. (1998). Sexual dimorphism in birds: why are there so many different forms of dimorphism?. Proceedings of the Royal Society of London. Series B: Biological Sciences265(1394), 397-407.

Rushton, J.P. (1988). Genetic similarity, mate choice, and fecundity in humans. Ethology and Sociobiology, 9, 328-335.

Rigby, N., & Kulathinal, R. J. (2015). Genetic architecture of sexual dimorphism in humans. Journal of cellular physiology230(10), 2304-2310.