Eikun siis jokaisen isobroidin myötä.
[list:10ws50ud]Blanchard and Klassen (1997) reported that each older brother increases the odds of being gay by 33%. This is now "one of the most reliable epidemiological variables ever identified in the study of sexual orientation." To explain this finding, it has been proposed that male fetuses provoke a maternal immune reaction that becomes stronger with each successive male fetus. Male fetuses produce HY antigens which are "almost certainly involved in the sexual differentiation of vertebrates." It is this antigen which maternal H-Y antibodies are proposed to both react to and 'remember'. Successive male fetuses are then attacked by H-Y antibodies which somehow decrease the ability of H-Y antigens to perform their usual function in brain masculinisation.[/list:u:10ws50ud]
 Blanchard and Klassen (1997). H-Y Antigen and Homosexuality in Men. Journal of Theoretical Biology, 185, 373-378.
 Blanchard, R. (1997). Birth order and sibling sex ratio in homosexual versus heterosexual males and females. Review of Sex Research, Vol. 8
Pretending to be certain about propositions for which no evidence is even conceivable—is both an intellectual and a moral failing. —Sam Harris