Handedness and sexual orientation
Encyclopedia
A relationship between handedness
and sexual orientation
has been suggested but not verified by a number of researchers, who report that heterosexual individuals are somewhat more likely to be right-handed than homosexual individuals. The relationship between handedness and sexual orientation has been reported within both sexes and may reflect the biological etiology
of homosexuality; recent work by Ray Blanchard
has linked the relationship to the fraternal birth order effect, which suggests that a man with several older brothers is more likely to be homosexual.
were found to be significantly more left-handed than heterosexual women (18% vs 10%), no significant differences were found between heterosexual and homosexual men with respect to hand preference.
Handedness
Handedness is a human attribute defined by unequal distribution of fine motor skills between the left and right hands. An individual who is more dexterous with the right hand is called right-handed and one who is more skilled with the left is said to be left-handed...
and sexual orientation
Sexual orientation
Sexual orientation describes a pattern of emotional, romantic, or sexual attractions to the opposite sex, the same sex, both, or neither, and the genders that accompany them. By the convention of organized researchers, these attractions are subsumed under heterosexuality, homosexuality,...
has been suggested but not verified by a number of researchers, who report that heterosexual individuals are somewhat more likely to be right-handed than homosexual individuals. The relationship between handedness and sexual orientation has been reported within both sexes and may reflect the biological etiology
Etiology
Etiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....
of homosexuality; recent work by Ray Blanchard
Ray Blanchard
Ray Milton Blanchard is an American-Canadian sexologist, best known for his research studies on pedophilia, gender dysphoria, and sexual orientation. He has also published research studies on phallometry and several paraphilias, including transvestism and autoerotic asphyxia.-Education and...
has linked the relationship to the fraternal birth order effect, which suggests that a man with several older brothers is more likely to be homosexual.
Mustanski et al., 2002 study
Mustanski et al. examined sexual orientation and hand preference in a sample of 382 men (205 heterosexual; 177 homosexual) and 354 women (149 heterosexual; 205 homosexual). Although homosexual womenLesbian
Lesbian is a term most widely used in the English language to describe sexual and romantic desire between females. The word may be used as a noun, to refer to women who identify themselves or who are characterized by others as having the primary attribute of female homosexuality, or as an...
were found to be significantly more left-handed than heterosexual women (18% vs 10%), no significant differences were found between heterosexual and homosexual men with respect to hand preference.
Lippa, 2003 study
Lippa examined sexual orientation and handedness in a sample of 812 men (351 heterosexual; 461 homosexual) and 1189 women (707 heterosexual; 472 homosexual). Homosexual men were 82% more likely to be left-handed than heterosexual men, but no significant differences were found between heterosexual and homosexual women in terms of handedness. When combining men and women into one large sample, homosexual individuals were 50% more likely to be left-handed than heterosexual individuals.Blanchard et al., 2006 study
Blanchard et al. argued that the fraternal birth order effect (the probability that a boy will be homosexual increases with the number of older brothers who have the same biological mother) appears to be limited to right-handed men. Moreover, the same study indicates that left-handed men without older brothers are more likely to be homosexual than non-right-handed men who have older brothers. As Blanchard et al. said in their report, "the odds of homosexuality is higher for men who have a non-right hand preference or who have older brothers, relative to men with neither of these features, but the odds for men with both features are similar to the odds for men with neither".Blanchard, 2008 Archives of Sexual Behavior study
A subsequent study by Blanchard found that both right-handed homosexual men and left-handed heterosexual men had a statistically significant number of older male siblings, but that there was no significant observable effect for right-handed heterosexual men or for left-handed homosexual men.Blanchard, 2008 Laterality study
Blanchard discussed ways in which the fraternal birth order effect and handedness could be explained in terms of the maternal immune hypothesis. In this, the mother is assumed to grow more immune to male antigens with each pregnancy, and thus produce a greater number of "anti-male" antibodies. He suggests two possibilities; that non-right-handed fetuses are less sensitive to the antibodies, or that the mothers of left-handed fetuses do not, for some reason, produce them.See also
- Biology and sexual orientationBiology and sexual orientationBiology and sexual orientation is the subject of research into the role of biology in the development of human sexual orientation. No simple, single cause for sexual orientation has been conclusively demonstrated, but research suggests that it is by a combination of genetic, hormonal, and...
- Prenatal hormones and sexual orientationPrenatal hormones and sexual orientationThe hormonal theory of sexuality holds that, just as exposure to certain hormones plays a role in fetal sex differentiation, such exposure also influences the sexual orientation that emerges later in the adult...