Archives of Sexual Behavior

, Volume 39, Issue 1, pp 75–80 | Cite as

Genetic and Environmental Effects on Same-sex Sexual Behavior: A Population Study of Twins in Sweden

  • Niklas Långström
  • Qazi Rahman
  • Eva Carlström
  • Paul Lichtenstein
Original Paper
First Online:
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Revised:
Accepted:

Abstract

There is still uncertainty about the relative importance of genes and environments on human sexual orientation. One reason is that previous studies employed self-selected, opportunistic, or small population-based samples. We used data from a truly population-based 2005–2006 survey of all adult twins (20–47 years) in Sweden to conduct the largest twin study of same-sex sexual behavior attempted so far. We performed biometric modeling with data on any and total number of lifetime same-sex sexual partners, respectively. The analyses were conducted separately by sex. Twin resemblance was moderate for the 3,826 studied monozygotic and dizygotic same-sex twin pairs. Biometric modeling revealed that, in men, genetic effects explained .34–.39 of the variance, the shared environment .00, and the individual-specific environment .61–.66 of the variance. Corresponding estimates among women were .18–.19 for genetic factors, .16–.17 for shared environmental, and 64–.66 for unique environmental factors. Although wide confidence intervals suggest cautious interpretation, the results are consistent with moderate, primarily genetic, familial effects, and moderate to large effects of the nonshared environment (social and biological) on same-sex sexual behavior.

Keywords

Sexual behavior Sexual orientation Population survey Twin study 
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Notes

Acknowledgments

We are grateful to Dr. Ray Blanchard who generously provided validation data from men referred to the Kurt Freund Laboratory at the Centre for Addiction and Mental Health in Toronto, Ontario. The Swedish Twin Registry is supported by unrestricted grants from the Swedish Department of Higher Education, the Swedish Research Council, and AstraZeneca. Niklas Långström is supported by the Swedish Research Council-Medicine.

References

  1. Bailey, J. M., Dunne, M. P., & Martin, N. G. (2000). Genetic and environmental influences on sexual orientation and its correlates in an Australian twin sample. Journal of Personality and Social Psychology, 78, 524–536.CrossRefPubMedGoogle Scholar
  2. Bailey, J. M., & Pillard, R. C. (1991). A genetic study of male sexual orientation. Archives of General Psychiatry, 48, 1089–1096.PubMedGoogle Scholar
  3. Bailey, J. M., Pillard, R. C., Dawood, K., Miller, M. B., Farrer, L. A., Trivedi, S., et al. (1999). A family history study of male sexual orientation using three independent samples. Behavior Genetics, 29, 79–86.CrossRefPubMedGoogle Scholar
  4. Bailey, J. M., Pillard, R. C., Neale, M. C., & Agyei, Y. (1993). Heritable factors influence sexual orientation in women. Archives of General Psychiatry, 50, 217–223.PubMedGoogle Scholar
  5. Baumeister, R. F. (2000). Gender differences in erotic plasticity: The female sex drive as socially flexible and responsive. Psychological Bulletin, 126, 347–374.CrossRefPubMedGoogle Scholar
  6. Caceres, C., Konda, K., Pecheny, M., Chatterjee, A., & Lyerla, R. (2006). Estimating the number of men who have sex with men in low and middle income countries. Sexually Transmitted Infections, 82(Suppl. 3), iii3–iii9.CrossRefPubMedGoogle Scholar
  7. 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, 271, 2217–2221.CrossRefGoogle Scholar
  8. Cochran, S. D., & Mays, V. M. (2000). Relation between psychiatric syndromes and behaviorally defined sexual orientation in a sample of the US population. American Journal of Epidemiology, 151, 516–523.PubMedGoogle Scholar
  9. Hamer, D. H., Hu, S., Magnuson, V. L., Hu, N., & Pattatucci, A. M. L. (1993). A linkage between DNA markers on the X chromosome and male sexual orientation. Science, 261, 321–327.CrossRefPubMedGoogle Scholar
  10. Hu, S., Pattatucci, A. M. L., Patterson, C., Li, L., Fulker, D. W., Cherny, S. S., et al. (1995). Linkage between sexual orientation and chromosome Xq28 in males but not in females. Nature Genetics, 11, 248–256.CrossRefPubMedGoogle Scholar
  11. Kendler, K. S., & Eaves, L. J. (1989). The estimation of probandwise concordance in twins: The effect of unequal ascertainment. Acta Geneticae Medicae et Gemellologiae, 38, 253–270.PubMedGoogle Scholar
  12. Kendler, K. S., Thornton, L. M., Gilman, S. E., & Kessler, R. C. (2000). Sexual orientation in a US national sample of twin and non-twin sibling pairs. American Journal of Psychiatry, 157, 1843–1846.CrossRefPubMedGoogle Scholar
  13. Kirk, K. M., Bailey, J. M., Dunne, M. P., & Martin, N. G. (2000). Measurement models for sexual orientation in a community twin sample. Behavior Genetics, 30, 345–356.CrossRefPubMedGoogle Scholar
  14. Lichtenstein, P., Sullivan, P. F., Cnattingius, S., Gatz, M., Johansson, S., Carlström, E., et al. (2006). The Swedish Twin Registry in the third millennium: An update. Twin Research and Human Genetics, 9, 875–882.CrossRefPubMedGoogle Scholar
  15. Lippa, R. A. (2006). Is high sex drive associated with increased sexual attraction to both sexes? It depends on whether you are male or female. Psychological Science, 17, 46–52.CrossRefPubMedGoogle Scholar
  16. Mustanski, B. S., DuPree, M. G., Nievergelt, C. M., Bocklandt, S., Schork, N. J., & Hamer, D. H. (2005). A genomewide scan of male sexual orientation. Human Genetics, 116, 272–278.CrossRefPubMedGoogle Scholar
  17. Neale, M. C. (1999). Mx: Statistical modeling (5th ed.). Richmond, VA: Virginia Commonwealth University.Google Scholar
  18. Rahman, Q. (2005). The neurodevelopment of human sexual orientation. Neuroscience and Biobehavioral Reviews, 29, 1057–1066.CrossRefPubMedGoogle Scholar
  19. Rahman, Q., Collins, A., Morrison, M., Orrells, J. C., Cadinouche, K., Greenfield, S., et al. (2007). Maternal inheritance and familial fecundity factors in male homosexuality. Archives of Sexual Behavior, doi: 10.1007/s10508-007-9191-2.
  20. Rice, G., Anderson, C., Risch, N., & Ebers, G. (1999). Male homosexuality: Absence of linkage to microsatellite markers at Xq28. Science, 284, 665–667.CrossRefPubMedGoogle Scholar
  21. Sanders, A. R., Cao, Q., Zhang, J., Badner, J. A., Goldin, L. R., Guroff, J. J., et al. (1998). Genetic linkage study of male homosexual orientation. Poster presented at the meeting of the American Psychiatric Association, Toronto, Canada.Google Scholar
  22. Sandfort, T. G., Bakker, F., Schellevis, F. G., & Vanwesenbeeck, I. (2006). Sexual orientation and mental and physical health status: Findings from a Dutch population survey. American Journal of Public Health, 96, 1119–1125.CrossRefPubMedGoogle Scholar
  23. Sandfort, T. G., de Graaf, R., Bijl, R. V., & Schnabel, P. (2001). Same-sex sexual behavior and psychiatric disorders. Findings from the Netherlands mental health survey and incidence study. Archives of General Psychiatry, 58, 85–91.CrossRefPubMedGoogle Scholar
  24. Sell, R. L., Wells, J. A., & Wypij, D. (1995). The prevalence of homosexual behavior and attraction in the United States, the United Kingdom and France: Results of national population-based samples. Archives of Sexual Behavior, 24, 235–248.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Niklas Långström
    • 1
  • Qazi Rahman
    • 2
    • 3
  • Eva Carlström
    • 4
  • Paul Lichtenstein
    • 4
  1. 1.Centre for Violence PreventionKarolinska InstitutetStockholmSweden
  2. 2.School of Biological SciencesQueen Mary-University of LondonLondonUK
  3. 3.Institute of PsychiatryKing’s College-University of LondonLondonUK
  4. 4.Department of Medical Epidemiology and BiostatisticsKarolinska InstitutetStockholmSweden

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