Forty-six homosexual men and women who were twins took part in a study of
their sexuality and that of their co-twin. Discordance for sexual
orientation in the monozygotic pairs confirmed that genetic factors are
insufficient explanation fo the development of sexual orientation. There
was a high level of shared knowledge of sexual orientation between members
of twin pairs, and a relatively high likelihood of sexual relations
occurring with same-sex co-twins at some time, particularly in
monozygotic pairs. The implications of these results for the study of
the origins of sexual orientation and for twin research are discussed.
© 1992. British Journal of Psychiatry.
To list of articles.