The 6 theories on the causes of homosexuality (according to science)

The question of the causes of homosexuality has been present in various scientific and philosophical discourse and research throughout the modern era. Inheriting the more traditional and conservative views of the Middle Ages that marked the beginnings of modern science, questions about sexual “minorities” have been approached and reformulated in important ways from different perspectives.

In this article, we’ll do a brief review of some of the the main scientific theories questioned on the causes of homosexuality. We also reflect on the implications of constantly questioning ourselves about the causes of what is portrayed as “the different.”

    What causes do we ask ourselves?

    In 1973, the American Psychological Association published the second version of the Diagnostic and Statistical Manuals of Mental Illness, with the goal of unifying clinical views on what is considered a disorder. This version includes a major change from the previous one: homosexuality withdrawn from the collection of troubles, With which, he ceased to be considered a mental pathology.

    It was only a first step, in part thanks to the social mobilizations of homosexuals themselves. For its part, the World Health Organization withdrew homosexuality from its international classification of diseases until the 1990s. And it was not until the first decade of the year 2000 that the APA published a official statement stating that there was no scientific validity to “corrective therapies” of homosexuality which continued to be implemented in different places.

    None of these measures seem to have resolved the doubts of many scientists and non-scientists as to why there are non-heterosexual people (and at the same time, they have not completely eliminated the social need to “correct” or expel).

    The question of the “different”

    As for the other “minority groups” (in which the difference with the hegemonic groups is strongly underlined), the question of knowing what are the causes of this difference does not cease to arise in various surveys; which, paradoxically, are constructed and present themselves as neutral.

    The above is in part the consequence that minority groups are often stereotyped from prejudices to danger, to wickedness, to human minors or even to inferiors. So, it is also common that, when it is not invisible to them, it is represented from the place of antagonism.

    The above means that, a priori, many research questions they took as a starting point and reference the heterosexual subject (male) and, from your body, experiences, desires, etc .; questions have been asked and answers to everything else.

    However, it is not surprising that even professional training in psychology and related fields continues to question the causes of homosexuality. In other words, at the heart of many research questions is an often invisible homophobic ideology. To illustrate this, we could do the brief exercise of asking ourselves why no one, or almost no one, questions (neither in research nor in everyday life) the causes of heterosexuality.

      Theories on the causes of homosexuality

      Thus, a series of studies, with different scientific perspectives, have been developed to explain homosexuality. So we go a brief review of the main proposals that have taken place, from psychoanalysis to genetic and psychosocial theories.

      1. Psychodynamic theories

      For Freudian psychoanalysis, psychic structuring it is strongly linked to psychosexual development. Sexual definition is a process that is not determined by anatomical features, but by predominant sexual identification and psychic choice of an object of desire. Homosexuality is here representative of a structuring in which an instinctive fixation has taken place towards the maternal figure as opposed to the father figure.

      This leads to the structuring of an object of desire which in this case corresponds to the same sex. This process does not necessarily occur in the same way in men and in women. In this context, Freud used the term “inverted” to refer to homosexuality, in an attempt to differentiate from the commonly used term: “perverted”.

      2. Biological determinism and genetic theories

      Perhaps the theories that have had the most impact on studies of homosexuality are those that they are part of biological paradigms. These range from Darwinian evolutionary theories to those which suggest that homosexuality is a consequence of certain genetic factors.

      From the above, it is often believed that homosexuality is counterproductive for the reproduction of the species, so some research suggests that this interpretation should be reconsidered, as the principle of natural selection does not necessarily apply in the case of heterosexuality-homosexuality.

      According to some of these theories, there is the possibility of a significant increase in fertility in women of same-sex maternal families. They also suggested that genetic factors linked to the X chromosome influence the homosexual orientation of men.

      3. Endocrinological theories

      Among the above and following explanations are research and theories on endocrine activity. In these it is suggested that homosexuality is consequence of peri or postnatal hormonal development; which in turn can be caused by different things, for example hormonal treatments of the mother during pregnancy.

      Likewise these theories they often highlight the role of testosterone in the development of the brain and nervous system. This hormone could cause masculinization of animals, especially during the gestation period. Deficiencies of testosterone in the perinatal development of men could lead to male homosexuality, and high levels of the same hormone would result in female homosexuality. There are even theories which suggest that the latter is visible in the size of the fingers of the right hand; in other words, depending on which finger is bigger than another, the hand could be an indicator of homosexuality.

      Finally, and on gestational development, it has been proposed that sexual orientation related to the immune response of the mother’s body, Which in turn is related to the development and activity of the Y chromosome (these theories apply to humans). Recent research has suggested that a certain reaction of the maternal body to proteins associated with this chromosome increases the likelihood of a man being homosexual, as well as various medical complications.

      4. Neurobiological theories

      In the 1990s, the American neurobiologist Simon Levay conducted various research on this subject. he compared the brain structures of gay men and straight men.

      In an attempt to reduce discrimination against gay men (he was gay); the neurobiologist proposed a series of answers which to this day remain valid and debated.

      According to his studies, there is a difference in the hypothalamus between straight and gay men. It is a nodule responsible for regulating the endocrine system, which in the case of gay men has similarities to the brains of heterosexual women. To these investigations were added various theories suggesting, for example, neurobiological differences in the development of men and women.

      5. Biological diversity and sexual dissent

      In the context of the opening of different scientific and philosophical currents, and as a result of different social movements that advocate the recognition of sexual diversity, queer theory has emerged. The latter assumes that gender and sex are social constructs (hence, sexual orientation in the broad sense is also). As such, these constructions generate a series of norms, desires and possibilities for action; as good as the practices of exclusion, segregation and pathologization.

      In this same context, the biologist Joan Roughgarden took up Darwinian theories of sexuality, but to overturn them. His research suggests the existence of different sexual genders, and questions the existence of a binary sex-gender (That is, what boils down to the possibility of being a man or a woman giving priority to heterosexuality). The latter becomes visible not only in humans, but also in many intersex animal species and species that have the potential to change biologically throughout their lives.

      6. Homosexuality in other species

      In the late 1990s, Bruce Bagemihl theorized sexual behavior in animals and proposed that, contrary to popular belief, this behavior takes different forms, even between animals of the same species. From his research, he reports that homosexual animal behavior is visible in over 500 species; ranging from primates to worms, including birds and mammals from different ecosystems.

      This behavior includes copulation, genital stimulation, and generally sexually exhibited behaviors between animals of the same sex. The same author discusses the evolutionary functions of homosexuality and suggests that they may not be the same for all species. Critics of this research point in the same direction, that of finding the reproductive and evolutionary advantages of sexual diversity from biological paradigms; which can also have repercussions on the disqualification of the latter.

      Bibliographical references:

      • Bagemihl, B. (1999). Biological exuberance: animal homosexuality and natural diversity. St. Martin Press: United States.
      • Skorska, M., Blanchard, R., Vanderlaan, DP and Bogaert, AF (2017). Gay-only male children: evidence of low birth weight and high rates of maternal abortion Sexual Behavior Archives, 46: 205-215.
      • Iemmola, F. and Camperio Ciani, A. (2009). New evidence for genetic factors influencing sexual orientation in men: increased female fertility in the maternal line. Sexual behavior files. Springer Netherlands, 38: 393-399.
      • Mattioli, G. (2009). Psychoanalysts in the Face of Homosexuality. Accessed July 6, 2018. Available at
      • Lantigua, I. (2005). When homosexuality was considered a disease. Accessed July 6, 2018.Available at
      • Roughgarden, J. (2004). Rainbow of evolution: diversity, gender and sexuality in nature and people. Rustic: Los Angeles, California.
      • Adkins-Regan, E. (1999). Biological exuberance: animal homosexuality and natural diversity. Bioscience, Oxford. 49 (11): 926-82.

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