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Arch Sex Behav (2008) 37:962969 DOI 10.1007/s10508-007-9191-2
ORIGINAL PAPER
Maternal Inheritance and Familial Fecundity Factors in Male Homosexuality
Qazi Rahman Anthony Collins Martine Morrison Jennifer Claire Orrells Khatija Cadinouche Sherene Greeneld Sabina Begum
Received: 4 May 2006 / Revised: 14 November 2006 / Accepted: 11 December 2006 / Published online: 31 July 2007 Springer Science+Business Media, LLC 2007
Abstract This study, following Camperio-Ciani, Corna, and Capiluppi [(2004), Proceedings of the Royal Society of London, Series B, Biological Sciences, 271, 22172221] aimed to examine the familial history of male homosexuality, and test the so-called fertile female hypothesis for this trait in a contemporary British sample. Using a comparative survey design, we found that white (comprising those of Anglo-European descent) and non-white (comprising ethnic Blacks, South Asians, East Asians, Hispanics, and Others) homosexual men (n = 147)had a signicant excess of maternal but not paternal line male homosexual relatives compared to heterosexual men (n = 155). We also found signicantly elevated fecundity of maternal aunts of white homosexual men compared to white heterosexual men, whereas non-white heterosexual men showed elevated fecundities of almost every class of relative compared to non-white homosexual men. No signicant excess of older brothers was found in homosexual compared to heterosexual men, irrespective of ethnic grouping. These data were discussed in relation to possible population-related factors in evolutionary explanations for human male homosexuality.
Keywords Male homosexuality Ethnicity Family history Fecundity Liability threshold Model Evolution
Introduction
The evolutionary biology of male homosexuality is of increasing theoretical interest as it constitutes a key variant in the human sexual phenotype. Some forms of homosexuality may have a heritable basis with further evidence for specic genetic loci (Bailey, Dunne, & Martin, 2000; Hamer, Hu, Magnuson, Hu, & Pattatucci, 1993; Hu et al., 1995; Mustanski et al., 2005; cf. Rice, Anderson, Risch, & Ebers, 1999), and it is also a persistently appearing trait over time in spite of its reduced tness differentials relative to male heterosexuality (Bell & Weinberg, 1978; for review, see Wilson & Rahman, 2005). Moreover, there have been two falsications of predictions derived from widely held explanations, such as kin selection (which proposes that homosexuals act as helpers in the nest; Wilson, 1975, 1978), leading to a renewed interest in explicit empirical testing of evolutionary...