The DOI matches its Crossref record; 26 of the 26 references it cites were found in a registry or an index.
Biological versus nonbiological older brothers and men’s sexual orientation
Open accessAbstract
The most consistent biodemographic correlate of sexual orientation in men is the number of older brothers (fraternal birth order). The mechanism underlying this effect remains unknown. In this article, I provide a direct test pitting prenatal against postnatal (e.g., social/rearing) mechanisms. Four samples of homosexual and heterosexual men (total n = 944), including one sample of men raised in nonbiological and blended families (e.g., raised with half- or step-siblings or as adoptees) were studied. Only biological older brothers, and not any other sibling characteristic, including nonbiological older brothers, predicted men’s sexual orientation, regardless of the amount of time reared with these siblings. These results strongly suggest a prenatal origin to the fraternal birth-order effect.
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“The conclusions appear to be based on a comparison of significance (for the coefficient of the number of older brothers) with nonsignificance (for the other coefficients), even though the differences between the coefficients do not appear to be statistically significant.”
From The Difference Between “Significant” and “Not Significant” is not Itself Statistically Significant (2006) · cites this paper as Bogaert (2006)
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Cites
A Difference in Hypothalamic Structure Between Heterosexual and Homosexual Men
LeVay, S. (1991) · Science · doi:10.1126/science.1887219 · Cited by 1,108
A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation
Hamer, D. H., Hu, S., Magnuson, V. L., Hu, N., & Pattatucci, A. M. L. (1993) · Science · doi:10.1126/science.8332896 · Cited by 871
Born to Rebel: Birth Order, Family Dynamics, and Creative Lives
Freese, J., Powell, B., & Sulloway, F. J. (1998) · Contemporary Sociology · doi:10.2307/2654718 · Cited by 631
Finger-length ratios and sexual orientation
Williams, T. J., Pepitone, M. E., Christensen, S. E., Cooke, B. M., Huberman, A. D., Breedlove, N. J., Breedlove, T. J., Jordan, C. L., & Breedlove, S. M. (2000) · Nature · doi:10.1038/35006555 · Cited by 582
Bailey, J. M., Dunne, M. P., & Martin, N. G. (2000) · Journal of Personality and Social Psychology · doi:10.1037//0022-3514.78.3.524 · Cited by 538
Maternal Stress Alters Plasma Testosterone in Fetal Males
Ward, I. L., & Weisz, J. (1980) · Science · doi:10.1126/science.7188648 · Cited by 369
Exotic becomes erotic: A developmental theory of sexual orientation.
Bem, D. J. (1996) · Psychological Review · doi:10.1037/0033-295x.103.2.320 · Cited by 333
Neurohormonal functioning and sexual orientation: A theory of homosexuality-heterosexuality.
Ellis, L., & Ames, M. A. (1987) · Psychological Bulletin · doi:10.1037//0033-2909.101.2.233 · Cited by 305
Homosexuality in men and number of older brothers
(1996) · American Journal of Psychiatry · doi:10.1176/ajp.153.1.27 · Cited by 284
Camperio-Ciani, A., Corna, F., & Capiluppi, C. (2004) · Proceedings of the Royal Society B Biological Sciences · doi:10.1098/rspb.2004.2872 · Cited by 275
Research works printed but not linked: 6
- 10.1037/0022-3514.78.3.524 · DOI · Paper page
- 10.1037/0022-3514.84.3.644 · DOI
- R. Blanchard Annu. Rev. Sex Res. 8, 27–67 (1997).
- 10.1037/0735-7044.111.6.1395 · DOI
- 10.1037/0033-2909.101.2.233 · DOI · Paper page
- I. L. Ward Handbook of Behavioral Neurobiology: Sexual Differentiation, eds A. A. Gerail, H. Moltz, I. L. Ward (Plenum, New York, 1992).
Cited by
The Difference Between “Significant” and “Not Significant” is not Itself Statistically Significant
Gelman, A., & Stern, H. (2006) · The American Statistician · doi:10.1198/000313006x152649 · Cited by 1,407
Neurotoxic autoantibodies mediate congenital cortical impairment of offspring in maternal lupus
Lee, J. Y., Huerta, P. T., Zhang, J., Kowal, C., Bertini, E., Volpe, B. T., & Diamond, B. (2009) · Nature Medicine · doi:10.1038/nm.1892 · Cited by 163
Metadata
- Authors
- Bogaert, A. F.
- Affiliations
- Brock University (CA)
- Corresponding author
- Bogaert, Anthony F.
- ORCID
- Bogaert, Anthony F.
- Venue
- Proceedings of the National Academy of Sciences
- Publisher
- National Academy of Sciences
- Published
- 2006-07-11
- Volume
- 103
- Issue
- 28
- Pages
- 10771-10774
- ISSN
- 0027-8424 (ISSN-L)
- 1091-6490
- PMC
- PMC1502306
- OpenAlex
- W2137113462
- Cited by
- 238
- References
- 26
- Citations by year
- 2026: 7 · 2025: 4 · 2024: 3 · 2023: 14 · 2022: 10 · 2021: 6 · 2020: 76 · 2019: 5 · 2018: 6 · 2017: 11 · 2016: 10 · 2015: 10 · 2014: 10 · 2013: 13 · 2012: 5
- FWCI
- 4.22
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Proceedings of the National Academy of Sciences (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Johns Hopkins University
- Social Sciences and Humanities Research Council of Canada
- Topics
- Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Sexual Differentiation and Disorders
- Social Sciences › Psychology › Social Psychology › LGBTQ Health, Identity, and Policy
- Social Sciences › Gender Studies › Gender and Feminist Studies
- Keywords
- sexual orientation, older brothers, biological siblings, adopted children, stepfamilies, prenatal origin, gay men, heterosexual men
- MeSH terms
- Adoption, Birth Order, Female, Humans, Male, Predictive Value of Tests, Sexual Behavior, Homosexuality, Male, Siblings
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Bibliographic data: Semantic Scholar, OpenAlex, Crossref.
Contains information from the Semantic Scholar Academic Graph Datasets, made available under the ODC Attribution License (ODC-BY 1.0).
Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.
