Dual-gender macro-chimeric tissue discordance is predicted to be a significant cause of human homosexuality and transgenderism

Brian P Hanley


I present literature evidence that suggests that human chimerism may be quite common, occurring in between 5% and 15% of people. Chimerism has been believed to be rare because it usually presents without visible phenotype. In addition to the documented occurrence of dual gender macrochimeras with true hermaphrodite phenotype, there are reports of the occurrence of other natural human macrochimeras. The literature reviewed in this paper suggests that such macrochimerism is much more common than usually appreciated. Chimerism occurs in a patchy manner, with male cells outgrowing female in macrochimerism causing the majority to be phenotypically male. The literature also suggests that the sex of nervous system tissue is the primary determinant in higher animals of sexual attraction.  From this, the existence of human macrochimeras in which large proportions of cells are male and female is predicted to have a correlation with homosexuality and transgender self-identification because in many such cases, the central nervous system, or crucial parts of it, will be of one sex and the gonads and body form will be of the opposite sex. I describe experiments to further clarify this hypothesis, which can also have potential benefit beyond this specific question. 


homosexuality; homosexual; transgenderism; transgender; chimerism; chimera; macro-chimerism; macro-chimera; tetragametic; dispermic; gender discordance


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