Thomas E. Bevan: The Psychobiology of Transsexualism and Transgenderism: A New View Based on Scientific Evidence

The Psychobiology of Transsexualism seeks to answer the question that so many transsexual people ask themselves: why do some people transition and live as the opposite sex? Essentially, Bevan is attempting to identify the root cause of transsexualism. The central thesis is that, because the first signs of transsexualism emerge early (usually around age 4 or 5), there is little room for casual factors other than genetics and epigenetic factors that alter DNA expression. Bevan argues that his two factor genetic-epigenetic theory of transsexualism is the only explanation that makes sense in light of the studies that have been done on transsexual people. In his two factor theory, the genetic factors include inherited genes from parents and novel genetic mutations at the time of conception. Epigenetic factors present during pregnancy also account for some causality, including exposure to environmental toxins, certain drugs, or simply maternal stress and/or trauma during the pregnancy. Epigenetics is a new field. When the phrase “epigenetic factors” is used it includes endogenous and exogenous chemical compounds interacting with genes to alter DNA expression. Bevan’s case is compelling, but further research will need to be done, particularly with epigenetics, in order to confirm his two factor theory of transsexualism. …