Various biomarkers are associated with male sexual orientation, suggesting possible underlying immunological, endocrine, and genetic mechanisms. However, the biomarkers have been studied in isolation, and the extent to which they interact or overlap remains unclear.
Researchers used a method called latent profile analysis to examine the distribution of 3 established biomarkers of sexual orientation—number of older brothers, left-handedness, and familiality of same-sex orientation—in more than 800 men, 18 years of age and older.
The analysis identified 4 subpopulations within the sample, which could be distinguished based on the biomarkers. None of the biomarkers were elevated among men in the first subgroup, whereas each of the remaining subgroups exhibited elevated levels for only one of the biomarkers.
The biomarker that was elevated differed for each subgroup. The 3 subgroups with elevated biomarker levels each had a higher proportion of nonheterosexual men compared with the subgroup that did not exhibit any elevated biomarker levels. The four subgroups differed significantly with respect to measures of gender nonconformity and personality traits such as femininity and agreeableness.
The results suggest the existence of subgroups of nonheterosexual men whose sexual orientation may be associated with different biological mechanisms, according to the authors.
Developmental pathways influencing male sexual orientation
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