Archives of Sexual Behavior

, Volume 39, Issue 1, pp 93–109

Biodemographic and Physical Correlates of Sexual Orientation in Men

  • Gene Schwartz
  • Rachael M. Kim
  • Alana B. Kolundzija
  • Gerulf Rieger
  • Alan R. Sanders
Original Paper

DOI: 10.1007/s10508-009-9499-1

Cite this article as:
Schwartz, G., Kim, R.M., Kolundzija, A.B. et al. Arch Sex Behav (2010) 39: 93. doi:10.1007/s10508-009-9499-1

Abstract

To better understand sexual orientation from an evolutionary perspective, we investigated whether, compared to heterosexual men, the fewer direct descendants of homosexual men could be counterbalanced by a larger number of other close biological relatives. We also investigated the extent to which three patterns generally studied separately––handedness, number of biological older brothers, and hair-whorl rotation pattern––correlated with each other, and for evidence of replication of previous findings on how each pattern related to sexual orientation. We surveyed at Gay Pride and general community festivals, analyzing data for 894 heterosexual men and 694 homosexual men, both groups predominantly (~80%) white/non-Hispanic. The Kinsey distribution of sexual orientation for men recruited from the general community festivals approximated previous population-based surveys. Compared to heterosexual men, homosexual men had both more relatives, especially paternal relatives, and more homosexual male relatives. We found that the familiality for male sexual orientation decreased with relatedness, i.e., when moving from first-degree to second-degree relatives. We also replicated the fraternal birth order effect. However, we found no significant correlations among handedness, hair whorl rotation pattern, and sexual orientation, and, contrary to some previous research, no evidence that male sexual orientation is transmitted predominantly through the maternal line.

Keywords

Sexual orientationFecundityEvolutionBirth orderHandednessHair whorl

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Gene Schwartz
    • 1
    • 2
  • Rachael M. Kim
    • 1
    • 2
  • Alana B. Kolundzija
    • 2
  • Gerulf Rieger
    • 1
  • Alan R. Sanders
    • 1
    • 2
    • 3
    • 4
  1. 1.Department of PsychologyNorthwestern UniversityEvanstonUSA
  2. 2.Behavior Genetics Unit, Center for Psychiatric Genetics, Department of Psychiatry and Behavioral SciencesNorthShore University HealthSystemEvanstonUSA
  3. 3.Department of Psychiatry and Behavioral Sciences, Feinberg School of MedicineNorthwestern UniversityEvanstonUSA
  4. 4.Research InstituteNorthShore University HealthSystemEvanstonUSA