Abstract
The second to fourth finger digit ratio (2D:4D ratio) is a sex-dimorphic characteristic in humans that may reflect relative levels of first trimester prenatal sex hormones. Low interdigital ratio has been associated with high levels of androgens. It has been reported in unrelated women that low 2D:4D ratio is associated with lesbian sexual orientation, but because of the nature of those samples, it was not possible to conclude whether lower ratio (and hypothetically, higher androgen levels) in lesbians are due to differences in genetics as opposed to differences in environment. To test the hypothesis that low 2D:4D in lesbians is due to differences in environment, interdigital ratio data were analyzed in a sample of female monozygotic (MZ) twins discordant for sexual orientation (1 twin was lesbian, the other was heterosexual; n = 7 pairs). A control group of female MZ twins concordant for sexual orientation (both twins were lesbian) was used as a comparison (n = 5 pairs). In the twins discordant for sexual orientation, the lesbian twins had significantly lower 2D:4D ratios on both the right and left hands than their heterosexual cotwins. There were no significant differences for either hand in the twins concordant for sexual orientation. Because MZ twins share virtually the same genes, differences in 2D:4D ratio suggest that low 2D:4D ratio is a result of differences in prenatal environment.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allen, L. S., & Gorski, R. A. (1992). Sexual orientation and the size of the anterior commissure in the human brain. Proceedings of the National Academy of Sciences of the United States of America, 89, 7199–7202.
Austin, E. J., Manning, J. T., McInroy, K., & Mathews, E. (in press). An investigation of the associations between personality, cognitive ability and digit ratio. Personality and Individual Differences.
Babler, W. J. (1991). Embyological development of epidermal ridges and their configurations. In C. C. Plato, R. M. Garruto, & B. A. Schaumann (Eds.), Dermatoglyphics: Science in transition (pp. 95–112). New York: Wiley.
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.
Blanchard, R. (1997). Birth order and sibling sex ratio in homosexual and heterosexual males and females. Annual Review of Sex Research, 8, 27–67.
Bracha, H. S., Torrey, E. F., Gottesman, I. I., Bigelow, L. B., & Cunniff, C. (1992). Second trimester markers of fetal size in schizophrenia: A study of monozygotic twins. American Journal of Psychiatry, 149, 1355–1361.
Brown, W. M., Hines, M., Fane, B., & Breedlove, S. M. (in press). Masculinized finger length patterns in human males and females with congenital adrenal hyperplasia. Hormones and Behavior.
Brown, W. M., Finn, C. J., Cooke, B. M., & Breedlove, S. M. (2002). Differences in finger length ratios between self-identified “butch” and “femme” lesbians. Archives of Sexual Behavior, 31, 117–121.
Byne, W., Tobet, S., Mattice, L. A., Lasco, M. S., Kemether, E., Edgar, M. A., et al. (2001). The interstitial nuclei of the human anterior hypothalamus: An investigation of variation with sex, sexual orientation, and HIV status. Hormones and Behavior, 40, 86–92.
Cederlof, R., Friberg, L., Johnson, E., & Kaij, L. (1961). Studies on similarity diagnosis in twins with the aid of mailed questionnaires. Acta Genetica Statistica Medicologica, 11, 338–362.
Garn, S. M., Burdi, A. R., Babler, W. J., & Stinson, S. (1975). Early prenatal attainment of adult metacarpal-phalangeal rankings and proportions. American Journal of Physical Anthropology, 43, 327–332.
George, R. (1930). Human finger types. Anatomical Record, 46, 199–204.
Hall, L. S. (2000a). Dermatoglyphic analysis of monozygotic twins discordant for sexual orientation. In N. M. Durham, K. M. Fox, & C. C. Plato (Eds.), The state of dermatoglyphics: The science of finger and palm prints (pp. 123–165). Lewiston, NY: Edwin Mellen.
Hall, L. S. (2000b). Dermatoglyphic analysis of total finger count in female monozygotic twins discordant for sexual orientation. Journal of Sex Research, 37, 315–320.
Hall, L. S. (2001a, Fall). Assessing 2nd to 4th interdigital ratio using inked prints. Newsletter of the American Dermatoglyphics Association, 24, 17–24.
Hall, L. S. (2001b). A relationship between markers of 1st trimester testosterone levels and drinking scores in males [Abstract]. Alcoholism: Clinical and Experimental Research 25, 151.
Hershberger, S. L. (1997). A twin registry study of male and female sexual orientation. Journal of Sex Research 34, 212–222.
Kinsey, A. C., Pomeroy, W. B., & Martin, C. E. (1948). Sexual behavior in the human male. Philadelphia: Saunders.
Klein, F., Sepekoff, B., & Wolf, T. J. (1985). Sexual orientation: A multi variable dynamic process. Journal of Homosexuality 11, 35–49.
LeVay, S. (1991). A difference in hypothalamic structure between heterosexual and homosexual men. Science, 253, 1034–1037.
LeVay, S. (1996). Queer science. Cambridge, MA: MIT Press.
Lutchmaya, S., Baron-Cohen, S., Raggatt, P., Knickermeyer, R., & Manning, J. T. (2002). 2nd to 4th digit ratios, fetal testosterone and estradiol. Manuscript submitted for publication.
Manning, J. T. (2001). Re: The ratio of 2nd to 4th digit length and age at presentation of breast cancer: A link with prenatal oestrogen? The Breast, 10, 355–357.
Manning, J. T. (2002). Digit ratio: A pointer to fertility, behavior, and health. New Brunswick, NJ: Rutgers University Press.
Manning, J. T, & Bundred, P. E. (2000). The ratio of 2nd to 4th digit length: A new predictor of disease predisposition? Medical Hypotheses, 54, 855–857.
Manning, J. T., Scutt, D., Wilson, J., & Lewis-Jones, D. I. (1998). The ratio of 2nd to 4th digit length: A predictor of sperm numbers and concentrations of testosterone, luteinizing hormone and oestrogen. Human Reproduction, 13, 3000–3004.
Manning, J. T., & Taylor, R. P. (2001). Second to fourth digit ratio and male ability in sport: Implications for sexual selection in humans. Evolution and Human Behavior, 22, 61–69.
Manning, J. T., Trivers, R. L., Singh, D., & Thornhill, R. (1999). The mystery of female beauty. Nature, 399, 214–215.
Martin, S., Manning, J. T., Trivers, R. L., Singh, D., Venkatramana, P., Henzi, P., et al. (2001, June). 2nd to 4th digit ratio and family size in England, Jamaica, India and South Africa. Paper presented at the annual meeting of the Human Behavior and Evolution Society, London, England.
McFadden, D. (2002). Masculinization effects in the auditory system. Archives of Sexual Behavior, 31, 93–105.
McFadden, D., & Champlin, C. A. (2000). Comparison of the auditory evoked potentials in heterosexual, homosexual, and bisexual males and females. Journal of the Association of Research in Otolaryncology, 1, 89–99.
McFadden, D., & Pasanen, E. G. (1998). Comparison of the auditory systems of heterosexuals and homosexuals: Click-evoked otoacoustic emissions. Proceedings of the National Academy of Sciences of the United States of America, 95, 2709–2713.
Nichols, R. C., & Bilbro, W.C. (1966). The diagnosis of twin zygosity. Acta Genetica Statistica Medicologica, 16, 265–275.
Phelps, V. R. (1952). Relative index finger length as a sex-influenced trait in man. American Journal of Human Genetics 4, 72–89.
Robinson, S. J., & Manning, J. T. (2000). The ratio of 2nd to 4th digit length and male homosexuality. Evolution and Human Behavior, 21, 333–345.
Sorenson-Jamison, C. S., Meier, R. J., & Campbell, B. C. (1993). Dermatoglyphic asymmetry and testosterone levels in normal males. American Journal of Physical Anthropology, 90, 185–198.
Tortorice, J. (2001, June). Gender identity, sexual orientation, and second-to-fourth digit ratio in females. Paper presented at the annual meeting of the Human Behavior and Evolution Society, London, England.
Tortorice, J. (2002). Independent development of gender identity and sexual orientation in females as reflected in second-to-fourth digit ratios. Manuscript submitted for publication.
Williams, T. J., Pepitone, M. E., Christensen, S. E., Cooke, B. M., Huberman, A. D., Breedlove, N. J., et al. (2000). Finger length ratios and sexual orientation. Nature, 404, 455–456.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hall, L.S., Love, C.T. Finger-Length Ratios in Female Monozygotic Twins Discordant for Sexual Orientation. Arch Sex Behav 32, 23–28 (2003). https://doi.org/10.1023/A:1021837211630
Issue Date:
DOI: https://doi.org/10.1023/A:1021837211630