Hair whorl direction and sexual orientation in human males.

Abstract

Hair whorl direction is a somatic feature that is organized early during neurodevelopment and unlikely to be influenced by social factors. This study aimed to replicate a widely reported association by A. J. S. Klar (2003) between counterclockwise hair whorl direction and homosexuality in men, using more objective methodology. The authors took digital photographs of parietal surface hair whorls from 100 heterosexual men and 100 homosexual men who were predominantly right-handed. These images were rated for clockwise and counterclockwise direction (for which no more than 1 hair whorl was present) by 2 raters unaware of sexual orientation. The authors found no significant difference between heterosexual and homosexual men in hair whorl direction, but the authors did replicate the fraternal birth order effect (more older brothers for homosexual men). Number of older sisters was positively correlated with counterclockwise hair whorls in heterosexual men. These data were discussed in relation to prenatal factors assumed to play a role in the neurodevelopment of male homosexuality.

Biodemographic and Physical Correlates of Sexual Orientation in Men

“…We found no significant relationship between hair whorl rotation pattern and handedness, contrasting with two studies (Beaton & Mellor, 2007;Klar, 2003), but consistent with the others (Annett, 1985;Collins, 1977;Jansen et al, 2007;Newman, 1934;Rahman et al, 2009). Also, we found no significant relationship between hair whorl rotation pattern and sexual orientation, contrasting with previous results in a much smaller sample (Klar, 2004), but consistent with another smaller sample (Rahman et al, 2009).…”

Fraternal Birth Order and Extreme Right-Handedness as Predictors of Sexual Orientation and Gender Nonconformity in Men

“…In addition, three large studies have reported no sexual orientation-related differences in handedness (Miller et al, 2008;Rahman, Clarke, & Morera, 2009;Schwartz, Kim, Kolundzija, Rieger, & Sanders, 2010). Scholars give the impression that there is consensus for an association between non-right handedness and homosexuality yet these three studies which do not report an association are notable in their sample size and use of continuous measures of handedness.…”

Who, What, Where, When (and Maybe Even Why)? How the Experience of Sexual Reward Connects Sexual Desire, Preference, and Performance

“…Of course, it is not known whether those neuroanatomical differences actually contribute to the sexual orientation of the individual or whether they simply reflect an unrelated endpoint of some differentiated developmental process. Biomarkers have also been suggested for a distinct (and not putatively feminized or demasculinized) ''gay'' genetic makeup in the expression of the X-linked marker Xq28 (Hamer, Hu, Magnuson, Hu, & Pattatucci, 1993), in the 2D:4D ratio of gay men relative to heterosexual men (e.g., Robinson & Manning, 2000), in a leftward directional handedness asymmetry (Martin, Puts, & Breedlove, 2008), hair-whorl direction (Rahman, Clarke, & Morera, 2009), visuospatial performance tasks (Collaer, Reimers, & Manning, 2007), and in the fraternal birth order effect (Blanchard, 2007;Blanchard & Lippa, 2007;Bogaert & Skorska, 2011;Rahman, 2005;Vasey & VanderLaan, 2007). Handedness and general IQ also appear as correlates in incarcerated male pedophiles (Cantor, Blanchard, Bobichaud, & Christensen, 2005;Cantor, Klassen et al, 2005), and cerebral white matter deficiencies in the superior fronto-occipital and right arcuate fasciculi have been found in incarcerated male pedophiles relative to an incarcerated nonpedophilic male population (Cantor et al, 2008), suggesting that frontal output (responsible for executive function and behavioral inhibition) of pedophilic individuals is compromised.…”