Skip to main content
SpringerLink
Log in

Male Sexual Orientation in Independent Samoa: Evidence for Fraternal Birth Order and Maternal Fecundity Effects

  • Original Paper
  • Published:
Archives of Sexual Behavior Aims and scope Submit manuscript

Abstract

In Western cultures, male androphiles tend to have greater numbers of older brothers than male gynephiles (i.e., the fraternal birth order effect). In the non-Western nation of Independent Samoa, androphilic males (known locally as fa’afafine) have been shown to have greater numbers of older brothers, older sisters, and younger brothers (Vasey & VanderLaan, 2007). It is unclear, however, whether the observed older brother effect, in the context of the additional sibling category effects, represented a genuine fraternal birth order effect or was simply associated with elevated maternal fecundity. To differentiate between these two possibilities, this study employed a larger, independent replication sample of fa’afafine and gynephilic males from Independent Samoa. Fa’afafine had greater numbers of older brothers and sisters. The replication sample and the sample from Vasey and VanderLaan were then combined, facilitating a comparison that showed the older brother effect was significantly greater in magnitude than the older sister effect. These results suggest that fraternal birth order and maternal fecundity effects both exist in Samoa. The existence of these effects cross-culturally is discussed in the context of biological theories for the development of male androphilia.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

Notes

  1. Within the context of the alternative explanation provided by Vasey and VanderLaan (2007), the Samoan population sex ratio corresponds to the equation: \( 1.0 9 = r_{\text{f}} s_{\text{f}} x + s_{\text{g}} ( 1- x), \) where 1.09 is the Samoan population sex ratio; r f is the reproductive rate of women who reproduce like the mothers of fa’afafine (i.e., greater number of children) relative to women who reproduce like the mothers of gynephilic males; s f is the offspring sex ratio of women who reproduce like the mothers of fa’afafine (i.e., expected offspring sex ratio); s g is the offspring sex ratio of women who reproduce like the mothers of gynephilic males (i.e., lower than expected offspring sex ratio); x is the proportion of reproductive women in the Samoan population who reproduce like the mothers of fa’afafine. As an illustration, estimating the equation’s parameters from descriptive statistics derived from the combined sample in the current study yields r f = 1.3, s f = 1.09, and s g = 0.89. Solving the equation to find the value of x shows that x = 0.38, which corresponds to an estimate of 38% of Samoan reproductive women who reproduce like the mothers of fa’afafine.

References

  • Bailey, J. M., & Zucker, K. J. (1995). Childhood sex-typed behavior and sexual orientation: A conceptual analysis and quantitative review. Developmental Psychology, 31, 43–55.

    Article  Google Scholar 

  • Bartlett, N. H., & Vasey, P. L. (2006). A retrospective study of childhood gender-atypical behavior in Samoan fa’afafine. Archives of Sexual Behavior, 35, 559–566.

    Article  Google Scholar 

  • Blanchard, R. (1997). Birth order and sibling sex ratio in homosexual versus heterosexual males and females. Annual Review of Sex Research, 8, 27–67.

    PubMed  Google Scholar 

  • Blanchard, R. (2004). Quantitative and theoretical analyses of the relation between older brothers and homosexuality in men. Journal of Theoretical Biology, 230, 173–187.

    Article  PubMed  Google Scholar 

  • Blanchard, R., & Bogaert, A. F. (1996). Homosexuality in men and number of older brothers. American Journal of Psychiatry, 153, 27–31.

    PubMed  Google Scholar 

  • Blanchard, R., & Klassen, P. (1997). H-Y antigen and homosexuality in men. Journal of Theoretical Biology, 185, 373–378.

    Article  PubMed  Google Scholar 

  • Blanchard, R., & Lippa, R. A. (2007). Birth order, sibling sex ratio, handedness, and sexual orientation of male and female participants in a BBC Internet research project. Archives of Sexual Behavior, 36, 163–176.

    Article  PubMed  Google Scholar 

  • Bogaert, A. F. (1998). Birth order and sibling sex ratio in homosexual and heterosexual non-White men. Archives of Sexual Behavior, 27, 467–473.

    Article  PubMed  Google Scholar 

  • Bogaert, A. F. (2003). Number of older brothers and sexual orientation: New tests and the attraction/behavior distinction in two national probability samples. Journal of Personality and Social Psychology, 84, 644–652.

    Article  PubMed  Google Scholar 

  • Bogaert, A. F. (2006). Biological versus nonbiological older brothers and men’s sexual orientation. Proceedings of the National Academy of Sciences USA, 103, 10771–10774.

    Article  Google Scholar 

  • Camperio Ciani, A., Corna, F., & Capiluppi, C. (2004). Evidence for maternally inherited factors favoring male homosexuality and promoting female fecundity. Proceedings of the Royal Society of London, Series B: Biological Sciences, 271, 2217–2221.

    Article  Google Scholar 

  • Cantor, J. M., Blanchard, R., Paterson, A. D., & Bogaert, A. F. (2002). How many gay men owe their sexual orientation to fraternal birth order? Archives of Sexual Behavior, 31, 63–71.

    Article  PubMed  Google Scholar 

  • Cardoso, F. L. (2005). Cultural universals and differences in male homosexuality: The case of a Brazilian fishing village. Archives of Sexual Behavior, 34, 103–109.

    Article  PubMed  Google Scholar 

  • Cardoso, F. L. (2009). Recalled sex-typed behavior in childhood and sports preferences in adulthood of heterosexual, bisexual, and homosexual men from Brazil, Turkey, and Thailand. Archives of Sexual Behavior, 38, 726–736.

    Article  PubMed  Google Scholar 

  • Danielsson, B., Danielsson, T., & Pierson, R. (1978). Polynesia’s third sex: The gay life starts in the kitchen. Pacific Islands Monthly, 49, 10–13.

    Google Scholar 

  • Davenport, W. H. (1987). An anthropological approach. In J. H. Geer & W. T. O’Donohue (Eds.), Theories of human sexuality (pp. 197–236). New York: Plenum Press.

    Google Scholar 

  • Iemmola, F., & Camperio Ciani, A. (2009). New evidence of genetic factors influencing sexual orientation in men: Female fecundity increase in the maternal line. Archives of Sexual Behavior, 38, 393–399.

    Article  PubMed  Google Scholar 

  • James, W. H. (1987). The human sex ratio: Part 1. A review of the literature. Human Biology, 59, 721–752.

    PubMed  Google Scholar 

  • James, W. H. (2000). Secular movements in sex ratios of adults and of births in populations during the past half-century. Human Reproduction, 15, 1178–1183.

    Article  PubMed  Google Scholar 

  • Johnson, M., Jackson, P., & Herdt, G. (2000). Critical regionalities and the study of gender and sexual diversity in South East and East Asia. Culture, Health, and Sexuality, 2, 361–375.

    Article  Google Scholar 

  • Jones, M. B., & Blanchard, R. (1998). Birth order and male homosexuality. Extension of Slater’s index. Human Biology, 70, 775–787.

    PubMed  Google Scholar 

  • King, M. D., Green, J., Osborn, D. P. J., Arkell, J., Hetherton, J., & Pereira, E. (2005). Family size in white gay and heterosexual men. Archives of Sexual Behavior, 34, 117–122.

    Article  PubMed  Google Scholar 

  • Kinsey, A. C., Pomeroy, W. B., & Martin, C. E. (1948). Sexual behavior in the human male. Philadelphia: Saunders.

    Google Scholar 

  • Mageo, J. M. (1992). Male transvestism and cultural change in Samoa. American Ethnologist, 19, 443–459.

    Article  Google Scholar 

  • Murray, S. O. (2000). Homosexualities. Chicago: University of Chicago Press.

    Google Scholar 

  • Poasa, K. H., Blanchard, R., & Zucker, K. J. (2004). Birth order in transgendered males from Polynesia: A quantitative study of Fa’afafine. Journal of Sex and Marital Therapy, 30, 12–23.

    Google Scholar 

  • Rahman, Q., Clarke, K., & Morera, T. (2009). Hair whorl direction and sexual orientation in human males. Behavioral Neuroscience, 123, 252–256.

    Article  PubMed  Google Scholar 

  • Rahman, Q., Collins, A., Morrison, M., Orrells, J. C., Cadinouche, K., Greenfield, S., et al. (2008). Maternal inheritance and familial fecundity factors in male homosexuality. Archives of Sexual Behavior, 37, 962–969.

    Article  PubMed  Google Scholar 

  • Rice, M. E., Harris, G. T., Lang, C., & Chaplin, T. C. (2008). Sexual preferences and recidivism of sex offenders with mental retardation. Sexual Abuse: A Journal of Research and Treatment, 20, 409–425.

    Article  Google Scholar 

  • Samoan Statistical Services Division of the Ministry of Finance. (2006). Census of Population. Retrieved December 1, 2006 from the World Wide Web: www.spc.org.nc/prism/Country/WS/stats/census_survey/census.htm.

  • Schmidt, J. (2003). Paradise lost? Social change and fa’afafine in Samoa. Current Sociology, 51, 417–432.

    Article  Google Scholar 

  • Schwartz, G., Kim, R. M., Kolundziji, A. B., Rieger, G., & Sanders, A. R. (2009). Biodemographic and physical correlates of sexual orientation in men. Archives of Sexual Behavior. doi:10.1007/s10508-009-9499-1.

  • Slater, E. (1958). The sibs and children of homosexuals. In D. R. Smith & W. M. Davidson (Eds.), Symposium on nuclear sex (pp. 79–83). London: Heinemann Medical Books.

    Google Scholar 

  • Suarez, B. K., & Przybeck, T. R. (1980). Sibling sex ratio and male homosexuality. Archives of Sexual Behavior, 9, 1–12.

    Article  PubMed  Google Scholar 

  • Tsoi, W. F., Kok, L. P., & Long, F. Y. (1977). Male transsexualism in Singapore: A description of 56 cases. British Journal of Psychiatry, 131, 405–409.

    Article  PubMed  Google Scholar 

  • Vasey, P. L., & Bartlett, N. H. (2007). What can the Samoan fa’afafine teach us about the Western concept of “Gender Identity Disorder in Childhood”? Perspectives in Biology and Medicine, 50, 481–490.

    Article  PubMed  Google Scholar 

  • Vasey, P. L., Pocock, D. S., & VanderLaan, D. P. (2007). Kin selection and male androphilia in Samoan fa’afafine. Evolution and Human Behavior, 28, 159–167.

    Article  Google Scholar 

  • Vasey, P. L., & VanderLaan, D. P. (2007). Birth order and male androphilia in Samoan fa’afafine. Proceedings of the Royal Society of London, Series B: Biological Sciences, 274, 1437–1442.

    Article  Google Scholar 

  • Vasey, P. L., & VanderLaan, D. P. (2008). Avuncular tendencies and the evolution of male androphilia in Samoan fa’afafine. Archives of Sexual Behavior. doi:10.1007/s10508-008-9443-9.

  • Vasey, P. L., & VanderLaan, D. P. (2009). Materteral and avuncular tendencies in Samoa: A comparative study of women, men and fa’afafine. Human Nature, 20, 269–281.

    Article  Google Scholar 

  • Vasey, P. L., & VanderLaan, D. P. (in press). An adaptive cognitive dissociation between willingness to help kin and non-kin children in Samoan fa’afafine. Psychological Science.

  • Whitham, F. L., & Zent, M. (1984). A cross-cultural assessment of early cross-gender behavior and familial factors in male homosexuality. Archives of Sexual Behavior, 13, 427–439.

    Article  Google Scholar 

  • Zucker, K. J., & Blanchard, R. (2003). Birth order in the Fakafefine. Journal of Sex and Marital Therapy, 29, 251–253.

    Article  PubMed  Google Scholar 

  • Zucker, K. J., Blanchard, R., Kim, T.-S., Pae, C.-U., & Lee, C. (2007). Birth order and sibling sex ratio in homosexual transsexual South Korean males: Effects of the male-preference stopping rule. Psychiatry and Clinical Neurosciences, 61, 529–533.

    Article  PubMed  Google Scholar 

Download references

Acknowledgments

The authors wish to thank Scott Allen, Resitara Apa, Ray Blanchard, Nancy Bartlett, Anthony Bogaert, Peniamina Tolovaa Fagai, Vester Fido Collins, Liulauulu Faaleolea Ah Fook, Vaasatia Poloma Komiti, Anita Latai, Martin Lalumière, Tyrone Laurenson, Gaualofa Matalavea, Nella Tavita-Levy, Sergio Pellis, David Pocock, Palanitina Toelupe, Trisha Tuiloma, Avalogo Togi A. Tunupopo, John Vokey, the Kuka family of Savai’i, the National University of Samoa, the Samoan AIDS Foundation, the National University of Samoa, the Government of Samoa, the Editor, and one anonymous referee. We are grateful to all of the individuals who agreed to participate in our study. We extend special thanks to Alatina Ioelu without whose help this study would not have been possible. Various stages of this research were supported by the University of Lethbridge, by a NSERC Canada Graduate Scholarship-D3 and a Sigma Xi, Grant in Aid of Research, to DPV as well as by a NSERC of Canada Discovery Grant to PLV.

Author information

Authors and Affiliations

  1. Department of Psychology, University of Lethbridge, Lethbridge, AB, T1K 3M4, Canada

    Doug P. VanderLaan & Paul L. Vasey

Authors
  1. Doug P. VanderLaan
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Paul L. Vasey
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Doug P. VanderLaan.

Rights and permissions

Reprints and permissions

About this article

Cite this article

VanderLaan, D.P., Vasey, P.L. Male Sexual Orientation in Independent Samoa: Evidence for Fraternal Birth Order and Maternal Fecundity Effects. Arch Sex Behav 40, 495–503 (2011). https://doi.org/10.1007/s10508-009-9576-5

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10508-009-9576-5

Keywords

Search

Navigation