Plasma testosterone and estradiol were determined and semen analysis was performed in 32 homosexuals. The degree of homosexuality was ascertained by use of the hetero-homosexual rating scale of Kinsey. A control group of 46 normal adult males of the same age distribution (20 to 33 yr) was used for the sex hormone determinations and another similar control group for semen analysis.
Plasma estradiol concentrations of the homosexual group were 2.24 ng/100 ml (median), 1.37 to 5.18 (range), the levels of the control group 1.77 and 1.07–2.95, respectively. Difference between the two groups is highly significant (P <.001, Wilcoxon test). No significant correlation between plasma estradiol and Kinsey rating was observed.
It was concluded that the elevated plasma estradiol concentrations of the homosexual group are a biological feature of this group and may be associated with the homosexual behavior. Plasma testosterone determination and semen analysis did not reveal any significant difference between the homosexual and the two control groups.