Male Homosexuality: Nature or Culture?


Emmanuele A. Jannini, MD, Course of Endocrinology and Medical Sexology, Department of Experimental Medicine, University of L'Aquila, L'Aquila 67100, Italy. Tel: +39 0862433530; Fax: +39 0862433523; E-mail:


Introduction.  Debate continues on whether or not male homosexuality (MH) is a result of biological or cultural factors. The debate persists despite the fact that these two sides have different abilities to create a scientific environment to support their cause. Biological theorists produced evidence, however, that these are not always robust. On the other hand, social theorists, without direct evidence confirming their positions, criticize, with good argument, methods and results of the other side. The aim of this Controversy is to understand the reasons of both perspectives.

Methods.  Two scientists (R.B. and A.C.C.) with expertise in the area of biology of MH were asked to contribute their opinions. The nurture position is discussed by a third expert in sexology (J.B.).

Main Outcome Measure.  Expert opinion supported by the critical review of the currently available literature.

Result.  The role of the Controversy's editor (E.A.J.) is to highlight the strengths and weaknesses of both sides. The two experts of the biological issue answer with their data to the questions: “Is male homosexuality partly explainable by immunology?” and “How is male homosexuality a Darwinian paradox?”, respectively. Genetic and immunological factors, birth order, and fertility of relatives are largely discussed. Finally, the expert sustaining the idea that culture and experiences are important determining factors in sexual orientation used a psychosocial and holistic perspective to explain his position.

Conclusions.  The JSM's readers should recognize that there are several biological factors in MH. However, these findings do not seem to be able to explain all cases of homosexuality. Some others may be due to particular environmental factors. The issue is complicated and multifactorial, suggesting that further research should be undertaken to produce the final answer to the question raised in this Controversy section. Jannini EA, Blanchard R, Camperio-Ciani A, and Bancroft J. Male homosexuality: Nature or culture? J Sex Med 2010;7:3245–3253.