The fraternal birth order effect is independent of potential confounds such as age, year of birth, and socioeconomic status. The male homosexual sibling who was interviewed displayed a strong identification with his mother via a feminine self-identification, the adoption of the housewife role in a homosexual marriage, and the adoption of the passive role in anal intercourse. Psychiatry and Clinical Neurosciences. Psychol Sci Public Interest. An in-utero maternal immune response has been hypothesized for this effect. So the fraternal birth order mechanism only causes males to be attracted to other males; whatever mechanism causes males to be pedophilic as opposed to teleiophilic i. It has be determined behaviorally to be biological.
Indeed, two samples from the high fertility Samoan population displayed simultaneous fraternal and 'sororal' birth order effects.
Having older brothers increases a man’s likelihood of being gay, study says
The behavior of the parents of this family was quite similar to the behavior of the parents in this study-a hostile and violent father and an affectionate and loving mother. Tony Bogaert found that biological brothers increase the odds of homosexuality in later-born males, even if they were reared in different households, whereas stepbrothers or adoptive brothers have no effect on sexual orientation. The team included researchers from Harvard and the University of Toronto. Given the scenario of mankind's survival, I have my doubts that any person, gay or bi, would let our species die out. A previous version of this story referred to higher concentrations of the protein instead of higher concentrations of antibodies to the proteins when describing the findings of the study.