In the 1960s and early 1970s, when medical procedures for altering sex were first being developed in the United States, approximately three out of every four people requesting a sex change were biological males who wished to be females (Green, 1974). Although most health professionals believe that males seeking sex reassignment still outnumber females, evidence indicates that the ratio has narrowed appreciably (Olsson & Moller, 2003). Male-to-female transsexualism has become increasingly common in developed nations, with an estimated prevalence of about 1 in 12,000 people having undergone male-to-female sex-reassignment procedures (Lawrence, 2007).
A vast accumulation of clinical literature has focused on the characteristics, causes (etiology), and treatment of transsexualism. Certain factors are well established. We know that most transsexuals are biologically normal individuals with healthy sex organs, intact internal reproductive structures, and the usual complement of XX or XY chromosomes (Meyer-Bahlburg, 2005). Furthermore, transsexualism is usually an isolated condition, not part of any general psychopathology, such as schizophrenia or major depression (Cohen-Kettenis & Gooren, 1999). What is less understood is why these individuals reject their anatomies.
Many transsexuals develop a sense of being at odds with their genital anatomy in early childhood; some recall identifying strongly with characteristics of the other sex at as early as 5, 6, or 7 years of age. In some cases these children’s discomfort is partially relieved by imagining themselves to be members of the other sex, but many of them eventually progress beyond mere imagining to actual cross-dressing. Less commonly, a strong identity with the other sex may not emerge until adolescence or adulthood.
The etiology of transsexualism is not clearly understood. Moreover, considerable controversy exists regarding the most appropriate clinical strategies for dealing with