These questionnaires consisted of items pertaining to the frequency of past attraction toward and sexual activity with males and females, with equal numbers of items pertaining to each sex. Most recently, Schagen et al. Thus, any significant differences identified between heterosexual and homosexual groups will exist despite, not because of, the inclusion of heterosexual probands in the homosexual groups. No one sits down one day and decides to be gay - or straight. Oh well, never mind. Table 6 shows the parameter estimates for the final multinomial equation, which describes the pattern of group differences.
Schagen et al.
They found, in a sample of men, that the fraternal birth order effect was contingent on handedness: Human development Sexual orientation Sibling. And there are other explanations floating around to explain the older brother effect.
In the third part of the article, Blanchard surveyed studies about fraternal birth order and found two studies that did not demonstrate the fraternal birth order effect in their homosexual groups.