Abstract
In reports of identical twins discordant for homosexuality, the homosexual twins showed the effeminacy syndrome in childhood. This has been considered evidence that the homosexuality comes from the twin himself. The possibility that the heterosexual twin was denying homosexuality has never been excluded. A pair of identical male twins discordant for homosexuality are reported. They showed significant differences in their penile volume responses to moving pictures of male and female nudes indicative of sexual orientations consistent with their statements. The homosexual twin showed the effeminacy syndrome. Aspects of the syndrome can be induced in mammals by altering their hormonal environment during some critical period in their intrauterine development. Discordance for homosexuality in identical twins could be due to one's being exposed to a different hormonal level during such a critical period.
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References
Bakwin, H. (1968). Deviant gender-role behavior in children: Relation to homosexuality.Pediatrics 41: 620–629.
Bakwin, H., and Bakwin, R. M. (1953). Homosexual behavior in children.J. Pediatr. 43: 108–111.
Barr, R. F., and McConaghy, N. (1971). Penile volume responses to appetitive and aversive stimuli in relation to sexual orientation and conditioning performance.Br. J. Psychiat. 119: 377–383.
Campion, E., and Tucker, G. (1973). A note on twin studies, schizophrenia and neurological impairment.Arch. Gen. Psychiat. 29: 460–464.
Davison, K., Brierley, H., and Smith, C. (1971). A male monozygotic twinship discordant for homosexuality: A repertory grid study.Br. J. Psychiat. 118: 675–682.
Freud, S. (1958). Psychoanalytic notes upon an autobiographical account of a case of paranoia. InThe Standard Edition of the Complete Psychological Works, Vol. 12, Hogarth, London.
Friedman, R. C., Wollesen, F., and Tendler, R. (1976). Psychological development and levels of sex steroids in male identical twins of divergent sexual orientation.J. Nerv. Ment. Dis. 163: 282–288.
Klintworth, G. K. (1962). A pair of male monozygotic twins discordant for homosexuality.J. Nerv. Ment. Dis. 135: 113–125.
McConaghy, N. (1967). Penile volume change to moving pictures of male and female nudes in heterosexual and homosexual males.Behav. Res. Ther. 5: 43–48.
McConaghy, N. (1975). Aversive and positive conditioning treatments of homosexuality.Behav. Res. Ther. 13: 309–319.
McConaghy, N. (1976). Is a homosexual orientation irreversible?Br. J. Psychiat. 129: 556–563.
McConaghy, N., Armstrong, M. S., Birrell, P. C., and Buhrich, N. (1979). The incidence of bisexual feelings and opposite sex behavior in medical students.J. Nerv. Ment. Dis. 67: 685–688.
Parker, N. (1964). Homosexuality in twins: A report on three discordant pairs.Br. J. Psychiat. 110: 489–495.
Rainer, J. D., Mesnikoff, A., Kolb, L. C., and Carr, A. (1960). Homosexuality and heterosexuality in identical twins.Psychosom. Med. 22: 251–250.
Reinish, J. M. (1974). Fetal hormones, the brain and human sex differences.Arch. Sex. Behav. 3: 51–90.
Ward, I. L. (1972). Prenatal stress feminizes and demasculinizes the behavior of males.Science 175: 82–84.
Wilson, R. S. (1970). Blood typing and twin zygosity.Hum Hered. 20: 30–56.
Zuger, B. (1966). Effeminate behavior present in boys from early childhood. I. The clinical syndrome and follow-up studies.J. Pediatr. 69: 1098–1107.
Zuger, B. (1976). Monozygotic twins discordant for homosexuality: Report of a pair and significance of the phenomenon.Comp. Psychiatry 17: 661–669.
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McConaghy, N., Blaszczynski, A. A pair of monozygotic twins discordant for homosexuality: Sex-dimorphic behavior and penile volume responses. Arch Sex Behav 9, 123–131 (1980). https://doi.org/10.1007/BF01542264
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DOI: https://doi.org/10.1007/BF01542264