Biodevelopmental Correlates of Sexual Orientation in Men: Evidence from a Polish Sample

Biological mechanisms proposed to play a role in the development of sexual orientation in men include hormonal, genetic, and immunological factors. The posited roles of these factors are not mutually exclusive; instead, they may be at play to different degrees in different individuals. Direct measurement of these influences is challenging; thus, researchers rely on putative markers. We collected data on five well-established markers in a sample of gay and heterosexual men. We then (1) compared the levels of those markers in gay and straight men, (2) identified latent profiles based on those markers, and (3) compared the proportions of gay and straight men within the profiles. Gay men reported less gender conformity in childhood, a higher proportion of older brothers, were more right-handed, had more non-heterosexual relatives, and had more feminized digit ratios. Of the six identified profiles, the most numerous, containing a significantly higher proportion of straight men, had masculine digit ratios, masculine behavior in childhood, and was the most right-handed. Proportions of gay and straight men did not differ in the profile with the most feminine digit ratio, the profile associated with the highest proportion of older brothers, and the profile associated with left-handedness. Two remaining profiles, associated with familiality, and the most feminine childhood gender behaviors, consisted predominantly of gay men. The study suggests that further investigations of differences within sexual orientation categories are warranted.