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Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia

Male homosexual preference (MHP) is an evolutionary enigma because it is partially heritable and imposes a fertility cost. In occidental societies, homosexual men are feminized at various levels and they have more older brothers than heterosexual men. To evaluate whether femininity and the fraternal...

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Autores principales: Nila, Sarah, Crochet, Pierre-Andre, Barthes, Julien, Rianti, Puji, Juliandi, Berry, Suryobroto, Bambang, Raymond, Michel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: SAGE Publications 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10358421/
https://www.ncbi.nlm.nih.gov/pubmed/31742436
http://dx.doi.org/10.1177/1474704919880701
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author Nila, Sarah
Crochet, Pierre-Andre
Barthes, Julien
Rianti, Puji
Juliandi, Berry
Suryobroto, Bambang
Raymond, Michel
author_facet Nila, Sarah
Crochet, Pierre-Andre
Barthes, Julien
Rianti, Puji
Juliandi, Berry
Suryobroto, Bambang
Raymond, Michel
author_sort Nila, Sarah
collection PubMed
description Male homosexual preference (MHP) is an evolutionary enigma because it is partially heritable and imposes a fertility cost. In occidental societies, homosexual men are feminized at various levels and they have more older brothers than heterosexual men. To evaluate whether femininity and the fraternal birth order (FBO) effect are universal features of MHP or not, we collected original data from homosexual men, heterosexual men, and heterosexual women from Java (Indonesia). Facial photographs were used to test whether homosexual faces are feminized when compared with heterosexual ones. We found that faces manipulated to resemble the average face of homosexual men are perceived as facially feminized, suggesting that homosexual men are facially feminized compared to heterosexual men, although a higher facial femininity was not captured by morphological analyses. Then, family data were used to detect differences in siblings’ composition between homosexuals and heterosexuals. Homosexual men displayed a higher number of older brothers than heterosexual men, even when sibship size was controlled for, suggesting that the FBO effect exists in Indonesian populations. Independent of sexual orientation, men with older brothers seem more feminized than those without older brothers, consistent with the immune origin of the FBO effect. In conclusion, MHP in Indonesia is partially feminized and they have more older brothers. Such features are also associated with MHP in other cultural contexts, suggesting a cross-cultural effect of men homosexual preference. An evolutionary explanation is available for the feminizing effect, although the FBO effect remains unexplained even if proximal mechanisms start to be identified.
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spelling pubmed-103584212023-09-07 Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia Nila, Sarah Crochet, Pierre-Andre Barthes, Julien Rianti, Puji Juliandi, Berry Suryobroto, Bambang Raymond, Michel Evol Psychol Original Article Male homosexual preference (MHP) is an evolutionary enigma because it is partially heritable and imposes a fertility cost. In occidental societies, homosexual men are feminized at various levels and they have more older brothers than heterosexual men. To evaluate whether femininity and the fraternal birth order (FBO) effect are universal features of MHP or not, we collected original data from homosexual men, heterosexual men, and heterosexual women from Java (Indonesia). Facial photographs were used to test whether homosexual faces are feminized when compared with heterosexual ones. We found that faces manipulated to resemble the average face of homosexual men are perceived as facially feminized, suggesting that homosexual men are facially feminized compared to heterosexual men, although a higher facial femininity was not captured by morphological analyses. Then, family data were used to detect differences in siblings’ composition between homosexuals and heterosexuals. Homosexual men displayed a higher number of older brothers than heterosexual men, even when sibship size was controlled for, suggesting that the FBO effect exists in Indonesian populations. Independent of sexual orientation, men with older brothers seem more feminized than those without older brothers, consistent with the immune origin of the FBO effect. In conclusion, MHP in Indonesia is partially feminized and they have more older brothers. Such features are also associated with MHP in other cultural contexts, suggesting a cross-cultural effect of men homosexual preference. An evolutionary explanation is available for the feminizing effect, although the FBO effect remains unexplained even if proximal mechanisms start to be identified. SAGE Publications 2019-11-19 /pmc/articles/PMC10358421/ /pubmed/31742436 http://dx.doi.org/10.1177/1474704919880701 Text en © The Author(s) 2019 https://creativecommons.org/licenses/by-nc/4.0/This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/ (https://creativecommons.org/licenses/by-nc/4.0/) ) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
spellingShingle Original Article
Nila, Sarah
Crochet, Pierre-Andre
Barthes, Julien
Rianti, Puji
Juliandi, Berry
Suryobroto, Bambang
Raymond, Michel
Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
title Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
title_full Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
title_fullStr Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
title_full_unstemmed Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
title_short Male Homosexual Preference: Femininity and the Older Brother Effect in Indonesia
title_sort male homosexual preference: femininity and the older brother effect in indonesia
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10358421/
https://www.ncbi.nlm.nih.gov/pubmed/31742436
http://dx.doi.org/10.1177/1474704919880701
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