Homosexual twin studies
Title: Homosexual Orientation in Twins: A Inform on 61 Pairs and Three Triplet Sets
REFERENCES
Bailey, J. M., and Pillard R. C. (). A genetic study of male sexual orientation. Arch. Gen. Psychiat.
Bouchard, T. J., Lykken, D. T., McGue, M., Segal, N. L., and Tellegen, A. (). Sources human psychological differences: The Minnesota study of wins reared apart. Science
Davison, K., Brierley, H., and Smith, C. (). A male monozygotic twinship discordant for homosexuality. Br. J. Psychiat.
Diamond, M. (). A critical evaluation of the ontogeny of human sexual behavior. Quart. Rev. Biol.
Diamond, M. (). Human sexual development: Biological Foundation for social development. In Beach, F. A. (ed), Human Sexuality in Four Perspectives, Johns Hopkins Press, Baltimore, MD, pp.
Diamond, M. (). Sexual identity and sex roles. In Bullough, V. (ed), The Frontiers of Sex Research, Prometheus, Buffalo, NY, pp.
Diamond, M. (). Sexual identity, monozygotic twins reared in discordant sex roles and a BBC follow-up. Arch. Sex. Behav.
Diamond, M. (). Homosexuality and bisexuality
TWIN STUDIES OF HOMOSEXUALITY
Why twin studies?
Twins potentially provide us with one of the most powerful techniques accessible for separating the influences of genetic and environmental factors on psychological and behavioural traits. An identical (monozygotic) twin has exactly the same genes as his cotwin. Fraternal (dizygotic) twins, on the other hand, are no more closely related genetically than are normal siblings, i.e. roughly 50% of their genes are the same.If index cases for a particular trait (e.g. homosexuality) are selected from twins in a given population, then the rate of concordance for that trait between the index case and his or her cotwin can be compared for monozygotic and dizygotic twins. It is assumed that the environment in which each member of a twin pair is reared is virtually identical, as twins are identical in age, and tend to possess very similar experiences during childhood (e.g. they get similar attention from their parents, attend the same schools, etc.). Therefore, any di
Why Do Some Identical Twins Have Adj Sexual Orientations?
by Justin Lehmiller
A growing amount of research suggests that sexual orientation has a genetic basis. In reality, scientists recently identified two specific genes that appear to differ between gay and straight men [1].
If sexual orientation is indeed genetically determined, it would be tempting to assume that identical twins would always have the matching orientation, right? If they have the exact same genes and our genes control our sexuality, this would appear like a beautiful logical conclusion. As it turns out, however, it’s not accurate.
Identical twins sometimes have different orientations. For example, one may be straight while the other is gay. So why is that?
In cases like this, some might contend that perhaps both twins are actually gay, but one just hasn’t advance out yet. In other words, maybe there isn’t a true discrepancy. But this idea has been refuted scientifically.
In a study where scientists looked at the sexual arousal patterns of identical twins with diverse sexualities—specifically, where one was
References
Bailey J.M., Dunne M.P., Martin N.G., Genetic and environmental influences on sexual orientation and its correlates in an Australian twin sample, „Journal of Personality and Social Psychology” , 78, –
Bearman P.S., Brückner H., Opposite-sex twins and adolescent same-sex attraction, „American Journal of Sociology” , , –
Bell J.T., Spector T.D., A twin approach to unraveling epigenetics, „Trends in Genetics” , 27 (3), –
Cedar H., Bergman Y., Programming of DNA methylaton patterns, „Annual Review of Biochemistry” , 81, 97–
Conaway J.W., Introduction to theme: chromatin, epigenetics and transcription, „Annual Review of Biochemistry” , 81, 61–
Fraga M.F., Ballestar E., Paz M.F., Ropero S., Ballestar M.L., Heine-Suner D.E., Cigudosa J.C., Uroiste M., Benite J., Boix-Chornet M., Sanchez-Aquiilera A., Ling C., Carrison E., Poulsen .P, Vaag A., Stephan Z., Spector T.D., Wu Y.Z., Plass C., Esteller M., Epiogenic differences arise during the lifetime of monozygotic twins, „Proceedings National Academy of Sciences USA” , (30), –9.
Garnets L.D., Sexual orientation in persp