Archives of Sexual Behavior

, Volume 25, Issue 5, pp 495–514 | Cite as

Birth order and sibling sex ratio in two samples of Dutch gender-dysphoric homosexual males

  • Ray Blanchard
  • Kenneth J. Zucker
  • Petty T. Cohen-Kettenis
  • Louis J. G. Gooren
  • J. Michael Bailey


Two studies were undertaken to confirm the previous findings that homosexual men in general tend to have a later than expected birth order and that extremely feminine homosexual men also tend to have a higher than expected proportion of brothers (i.e. a highersibling sex ratio). Subjects in Study 1 were Dutch, adult and adolescent, biological male patients with gender dysphoria (persistent and recurrent desires to belong to the opposite sex), who were undergoing treatment with feminizing hormones. These comprised 83 patients who reported sexual attraction to other males (the homosexual group) and 58 who reported sexual attraction to females or equal attraction to males and females (the nonhomosexual group). Subjects in Study 2 were Dutch adolescent male patients at another hospital. The homosexual group consisted of 21 gender-dysphoric homosexual teenagers referred to a gender identity clinic for children and adolescents. The control group were 21 adolescent males referred to the child psychiatry department of the same hospital for reasons other than gender identity disorder, homosexuality, or transvestism. These were individually matched to the homosexual subjects on age and sibship size. In both studies, the homosexual group had a significantly later average birth order than the comparison group. In Study 1, the homosexual group had a significantly elevated sibling sex ratio; this was not tested in Study 2 because of its small sample size. These studies add to the mounting evidence that late birth orders are common to all homosexual samples and that elevated sibling sex ratios are an additional characteristic of extremely feminine ones.

Key Words

homosexuality transsexualism gender dysphoria gender identity disorder birth order sibling sex ratio 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Ackerman-Ross, S., and Khanna, P. (1989). The relationship of high quality day care to middle-class 3-year-olds' language performance.Early Childhood Research Quarterly 4: 97–116.CrossRefGoogle Scholar
  2. American Psychiatric Association. (1987).Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., rev., American Psychiatric Association, Washington, DC.Google Scholar
  3. Bailey, J. M., and Pillard, R. C. (1991). A genetic study of male sexual orientation.Arch. Gen. Psychiat. 48: 1089–1096.PubMedGoogle Scholar
  4. Bailey, J. M., and Zucker, K. J. (1995). Childhood sex-typed behavior and sexual orientation: A conceptual analysis and quantitative review.Dev. Psychol. 31: 43–55.CrossRefGoogle Scholar
  5. Berglin, C. G. (1982). Birth order as a quantitative expression of date of birth.J. Epidemiol. Commun. Health. 36: 298–302.CrossRefGoogle Scholar
  6. Berglin, C. G. (1985). Male antigenicity and parity.Behav. Brain Sci. 8: 442–443.Google Scholar
  7. Bigner, J. J. (1972). Sibling influence on sex-role preference of young children.J. Genet. Psychol. 121: 271–282.PubMedGoogle Scholar
  8. Bijur, P. E., Golding, J., and Kurzon, M. (1988). Childhood accidents, family size and birth order.Soc. Sci. Med. 26: 839–843.PubMedCrossRefGoogle Scholar
  9. Birtchnell, J. (1971). Birth rank and mental illness.Nature 234: 485–487.PubMedCrossRefGoogle Scholar
  10. Blanchard, R. (1985). Typology of male-to-female transsexualism.Arch. Sex. Behav. 14: 247–261.PubMedCrossRefGoogle Scholar
  11. Blanchard, R. (1988). Nonhomosexual gender dysphoria.J. Sex Res. 24: 188–193.Google Scholar
  12. Blanchard, R. (1989a). The classification and labeling of nonhomosexual gender dysphorias.Arch. Sex. Behav. 18: 315–334.PubMedCrossRefGoogle Scholar
  13. Blanchard, R. (1989b). The concept of autogynephilia and the typology of male gender dysphoria.J. Nerv. Ment. Dis. 177: 616–623.PubMedGoogle Scholar
  14. Blanchard, R. (1993a). The she-male phenomenon and the concept of partial autogynephilia.J. Sex Marital Ther. 19: 69–76.PubMedGoogle Scholar
  15. Blanchard, R. (1993b). Partial versus complete autogynephilia and gender dysphoria.J. Sex Marital Ther. 19: 301–307.PubMedGoogle Scholar
  16. Blanchard, R., and Bogaert, A. F. (1996). Homosexuality in men and number of older brothers.Am. J. Psychiat. 153: 27–31.PubMedGoogle Scholar
  17. Blanchard, R., and Bogaert, A. F. (in press). Biodemographic comparisons of homosexual and heterosexual men in the Kinsey interview data.Arch. Sex. Behav. Google Scholar
  18. Blanchard, R., and Sheridan, P. M. (1992). Sibship size, sibling sex ratio, birth order, and parental age in homosexual and nonhomosexual gender dysphorics.J. Nerv. Ment. Dis. 180: 40–47.PubMedGoogle Scholar
  19. Blanchard, R., and Zucker, K. J. (1994). Reanalysis of Bell, Weinberg, and Hammersmith's data on birth order, sibling sex ratio, and parental age in homosexual men.Am. J. Psychiat. 151: 1375–1376.PubMedGoogle Scholar
  20. Blanchard, R., Zucker, K. J., Bradley, S. J., and Hume, C. S. (1995). Birth order and sibling sex ratio in homosexual male adolescents and probably prehomosexual feminine boys.Dev. Psychol. 31: 22–30.CrossRefGoogle Scholar
  21. Bourguet, C. C., and McArtor, R. E. (1989). Unintentional injuries: Risk factors in preschool children.Am. J. Dis. Child. 143: 556–559.PubMedGoogle Scholar
  22. Brody, C. J., and Steelman, L. C. (1985). Sibling structure and parental sex-typing of children's household tasks.J. Marr. Fam. 47: 265–273.CrossRefGoogle Scholar
  23. Brown, L. M., and Weinraub, M. (1980). Sibling status: Implications for sex-typed toy preferences and awareness of sex-role stereotypes in 2- to 3-year-old children. Unpublished manuscript, Temple University, Philadelphia, PA.Google Scholar
  24. Camilleri, A. P., and Cremona, V. (1970). The effect of parity on birthweight.J. Obstet. Gynaecol. Br. Commonwealth 77: 145–147.Google Scholar
  25. Chahnazarian, A. (1988). Determinants of the sex ratio at birth: Review of recent literature.Soc. Biol. 35: 214–235.PubMedGoogle Scholar
  26. Cobb, J. A. (1914). The alleged inferiority of the first-born.Eugenics Rev. 5: 357–359.Google Scholar
  27. Cohen, J. (1988).Statistical Power Analysis for the Behavioral Sciences, 2nd ed., Erlbaum, Hillsdale, NJ.Google Scholar
  28. Cohen, S. E., and Beckwith, L. (1977). Caregiving behaviors and early cognitive development as related to ordinal position in preterm infants.Child Dev. 48: 152–157.PubMedCrossRefGoogle Scholar
  29. Diamond, M., Rust, N., and Westphal, U. (1969). High-affinity binding of progesterone, testosterone and cortisol in normal and androgen treated guinea pigs during various reproductive stages: Relationship to masculinization.Endocrinology 84: 1143–1151.PubMedCrossRefGoogle Scholar
  30. Green, R. (1987).The “Sissy Boy Syndrome” and the Development of Homosexuality, Yale University Press, New Haven, CT.Google Scholar
  31. Grotevant, H. D. (1978). Sibling constellations and sex-typing of interests in adolescence.Child Dev. 49: 540–542.CrossRefGoogle Scholar
  32. Gualtieri, T., and Hicks, R. E. (1985). An immunoreactive theory of selective male affliction.Behav. Brain Sci. 8: 427–441.CrossRefGoogle Scholar
  33. Hamer, D. H., Hu, S., Magnuson, V. L., Hu, N., and Pattatucci, A. M. L. (1993). A linkage between DNA markers on the X-chromosome and male sexual orientation.Science 261: 321–327.PubMedGoogle Scholar
  34. Hare, E. H., and Moran, P. A. P., (1979). Parental age and birth order in homosexual pateints: A replication of Slater's study.Br. J. Psychiat. 134: 178–182.Google Scholar
  35. Hare, E. H., and Price, J. S. (1969). Birth order and family size: Bias caused by changes in birth rate.Br. J. Psychiat. 115: 647–657.Google Scholar
  36. Hare, E. H., and Price, J. S. (1974). Birth order and birth rate bias: Findings in a representative sample of the adult population of Great Britain.J. Biosoc. Sci. 6: 139–150.Google Scholar
  37. Horwitz, S. M., Morgenstern, H., DiPietro, L., and Morrison, C. L. (1988). Determinants of pediatric injuries.Am. J. Dis. Child. 142: 605–611.PubMedGoogle Scholar
  38. Jagers, P. (1982). How probable is it to be first born? and other branching-process applications to kinship problems.Math. Biosci. 59: 1–15.CrossRefGoogle Scholar
  39. James, W. H. (1987a). The human sex ratio. Part 1: A review of the literature.Hum. Biol. 59: 721–752.PubMedGoogle Scholar
  40. James, W. H. (1987b). The human sex ratio. Part 2: A hypothesis and a program of research.Hum. Biol. 59: 873–900.PubMedGoogle Scholar
  41. James, W. H. (1990). The hypothesized hormonal control of human sex ratio at birth—an update.J. Theoret. Biol. 143: 555–564.Google Scholar
  42. James, W. H. (1992). The hypothesized hormonal control of mammalian sex ratio at birth—a second update.J. Theoret. Biol. 155: 121–128.CrossRefGoogle Scholar
  43. Jensch, K. (1941). Weiterer Beitrag zur Genealogie der Homosexualität [A further contribution to the genealogical study of homosexuality].Arch. Psychiat. Nervenkr. 112: 679–696.CrossRefGoogle Scholar
  44. Kallmann, F. J. (1952). Twin and sibship study of overt male homosexuality.Am. J. Hum. Genet. 4: 136–146.PubMedGoogle Scholar
  45. Katz, P. A., and Boswell, S. L. (1984). Sex-role development and the one-child family. In Falbo, T. (ed.),The Single-Child Family, Guilford, New York, pp. 63–116.Google Scholar
  46. Koch, H. L. (1956). Sissiness and tomboyishness in relation to sibling characteristics.J. Genet. Psychol. 88: 231–244.PubMedGoogle Scholar
  47. Lang, T. (1940). Studies on the genetic determination, of homosexuality.J. Nerv. Ment. Dis. 92: 55–64.CrossRefGoogle Scholar
  48. Lang, T. (1960). Die Homosexualität als genetisches Problem [Homosexuality as a genetic problem].Acta Genet. Med. Gemellol. 9: 370–381.PubMedGoogle Scholar
  49. Laosa, L. M., and Brophy, J. E. (1972). Effects of sex and birth order on sex-role development and intelligence among kindergarten children.Dev. Psychol. 6: 409–415.CrossRefGoogle Scholar
  50. Leventhal, G. S. (1970). Influence of brothers and sisters on sex-role behavior.J. Pers. Soc. Psychol. 16: 452–465.CrossRefGoogle Scholar
  51. Lewis, M., and Kreitzberg, V. S. (1979). Effects of birth order and spacing on mother-infant interactions.Dev. Psychol. 15: 617–625.CrossRefGoogle Scholar
  52. Libber, S. M., and Stayton, D. J. (1984). Childhood burns reconsidered: The child, the family, and the burn injury.J. Trauma 24: 245–252.PubMedGoogle Scholar
  53. MacCulloch, M. J., and Waddington, J. L. (1981). Neuroendocrine mechanisms and the aetiology of male and female homosexuality.Br. J. Psychiat. 139: 341–345.Google Scholar
  54. Manheimer, D. I., Dewey, J., Mellinger, G. D., and Corsa, L. (1966). Fifty thousand child-years of accidental injuries.Public Health Rep. 81: 519–533.PubMedGoogle Scholar
  55. Martin, J. F. (1994). Changing sex ratios: The history of Havasupai fertility and its implications for human sex ratio variation.Curr. Anthropol. 35: 255–266.CrossRefGoogle Scholar
  56. Meulenberg, P. M. M., and Hofman, J. A. (1991). Maternal testosterone and fetal sex.J. Steroid Biochem. Molec. Biol. 39: 51–54.PubMedCrossRefGoogle Scholar
  57. Money, J., and Lamacz, M. (1984). Gynemimesis and gynemimetophilia: Individual and crosscultural manifestations of a gender-coping strategy hitherto unnamed.Comprhen. Psychiat. 25: 392–403.CrossRefGoogle Scholar
  58. Moore, D. H., and Gledhill, B. L. (1988). How large should my study be so that I can detect an altered sex ratio?Fertil. Steril. 50: 21–25.PubMedGoogle Scholar
  59. Nixon, J., and Pearn, J. (1978). An investigation of socio-demographic factors surrounding childhood drowning accidents.Soc. Sci. Med. 12: 387–390.PubMedGoogle Scholar
  60. Pauly, I. B. (1992). Terminology and classification of gender identity disorders.J. Psychol. Hum. Sex. 5: 1–14.CrossRefGoogle Scholar
  61. Price, J. S., and Hare, E. H. (1969). Birth order studies: Some sources of bias.Br. J. Psychiat. 115: 633–646.CrossRefGoogle Scholar
  62. Schachter, F. F. (1982). Sibling deidentification and split-parent identification: A family tetrad. In Lamb, M. E., and Sutton-Smith, B. (eds.),Sibling Relationships, Erlbaum, Hillsdale, NJ, pp. 123–151.Google Scholar
  63. Sieff, D. F. (1990). Explaining biased sex ratios in human populations: A critique of recent studies.Curr Anthropol. 31: 25–35.CrossRefGoogle Scholar
  64. Slater, E. (1958). The sibs and children of homosexuals. In Smith, D. R., and Davidson, W. M. (eds.),Symposium on Nuclear Sex, Heinemann, London, pp. 79–83.Google Scholar
  65. Slater, E. (1962). Birth order and maternal age of homosexuals.Lancet 1: 69–71.PubMedCrossRefGoogle Scholar
  66. Suarez, B. K., and Przybeck, T. R. (1980). Sibling sex ratio and male homosexuality.Arch. Sex. Behav. 9: 1–12.PubMedCrossRefGoogle Scholar
  67. Sutton-Smith, B., Roberts, J. M., and Rosenberg, B. G. (1964). Sibling associations and role involvement.Merrill-Palmer Quart. 10: 25–38.Google Scholar
  68. Vroegh, K. (1971). The relationship of birth order and sex of siblings to gender role identity.Dev. Psychol. 4: 407–411.CrossRefGoogle Scholar
  69. West, D. J. (1977).Homosexuality Re-examined, University of Minnesota Press, Minneapolis.Google Scholar
  70. Whitam, F. L., Diamond, M., and Martin, J. (1993). Homosexual orientation in twins: A report on 61 pairs and three triplet sets.Arch. Sex. Behav. 22: 187–206.PubMedCrossRefGoogle Scholar
  71. Whitam, F. L., and Zent, M. (1984). A cross-cultural assessment of early cross-gender behavior and familial factors in male homosexuality.Arch. Sex. Behav. 13: 427–439.PubMedCrossRefGoogle Scholar
  72. Zucker, K. J., and Blanchard, R. (1994). Reanalysis of Bieber et al.'s 1962 data on sibling sex ratio and birth order in male homosexuals.J. Nerv. Ment. Dis. 182: 528–530.PubMedGoogle Scholar

Copyright information

© Plenum Publishing Corporation 1996

Authors and Affiliations

  • Ray Blanchard
    • 1
  • Kenneth J. Zucker
    • 2
  • Petty T. Cohen-Kettenis
    • 3
  • Louis J. G. Gooren
    • 4
  • J. Michael Bailey
    • 5
  1. 1.Gender Identity ClinicClarke Institute of PsychiatryTorontoCanada
  2. 2.Child and Adolescent Gender Identity Clinic, Child and Family Studies CentreClarke Institute of PsychiatryTorontoCanada
  3. 3.Rudolf Magnus Institute for Neurosciences, Department of Child and Adolescent PsychiatryUniversity HospitalUtrechtThe Netherlands
  4. 4.Department of EndocrinologyFree University HospitalAmsterdamThe Netherlands
  5. 5.Department of PsychologyNorthwestern UniversityEvanston

Personalised recommendations