Is transsexualism hereditary ?

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There have been only a few reports of single pairs of identical twins.  There are at this point as many discordant as concordant pairs,  but it is still too early to judge what this means.  One monozygotic pair was reported to be discordent for transsexualism  (Garden & Rothery, 1992) while another was found to be concordant (Hyde & Kenna, 1977). The study of the genetics of transsexualism is very difficult because of social opprobrium and also because transsexualism is a very rare condition.   About one person in every twenty-two thousand undergoes a sex-change operation in those countries where the operation is readily available.   This makes it very hard to recruit sizable cohorts of identical and fraternal twins for genetic studies.   One study investigated a large cohort of male-to-female transsexuals.   The researchers discretely asked family members to fill out a questionnaire.  The brothers of the transsexuals tended to be less often married or in common law heterosexual marriage or even to date women than normal controls (Blanchard & Sheridan, 1992).  This difference was statistically significant.  The authors of this study concluded that this suggested a hereditary basis for transsexualism.   Another idirect piece of evidence supporting the existence of a hereditary factor is the recent finding to the effect that male-to-female transsexuals have fewer maternal uncles (similar to one prior study of gay men).   Obviously,  it would be reasonable to start searching for a transsexualism gene on the X chromosome.

On the other hand,  environmental conditions may,  it seems,  suffice,  on occasion to produce transsexuality.   A few sections down,  I mention special child-rearing conditions which seem to contribute to the development of transsexualism.   Also,   transsexualism can even occur as a group phenomenon,  largely culturally determined.   The   hijra   (a signifying eunuch/transvestite in one of India’s languages), an institutionalized 3rd gender role in India, is neither male nor female but contains elements of both. As devotees of the Mother Goddess Bahuchara Mata, their sacred powers are contingent on their asexuality.  In reality, however, many   hijras   are prostitutes. This sexual activity undermines their culturally valued sacred role.