Sexual orientation and handedness in men and women: A meta-analysis

Recent findings suggest that sexual orientation has an early neurodevelopme ntal basis. Handedness, a behavioral marker of early neurodevelopment, has been associated with sexual orientation in some studies but not in others. The authors conducted a meta-analysis of 20 studies that compared the rates of non-right-handedness in 6.987 homosexual (6,182 men and 805 women) and 16,423 heterosexual (14,808 men and 1,615 women) participants. Homosexual p articipants had 39% greater odds of being non-right-handed. The correspondi ng values for homosexual men (20 contrasts) and women (9 contrasts) were 34 % and 91%, respectively. The results support the notion that sexual orienta tion in some men and women has an early neurodevelopmental basis, but the f actors responsible for the handedness-sexual orientation association requir e elucidation. The authors discuss 3 possibilities: cerebral laterality and prenatal exposure to sex hormones, maternal immunological reactions to the fetus, and developmental instability.