It is easier to mutate a base form, than to reverse the mutation once it has already occurred. Likewise, facial and body hair are permanent and can only be removed by physical effort, such as electrolysis. Breasts are permanent, and must be removed by surgery once grown. Hormones alter the distribution of fat in the body, of muscle tissue, and alter the basic chemistry of the brain, affecting perception and function. But for large scale fundamental structures, only surgery will suffice.
Bones are permanent once formed, as are sex organs.
To have proper genitals, the transsexual must undergo sex reassignment surgery. There are those who are not driven to complete a full sex reassignment to fit an easily defined, polarized gender. It should be understood that gender is NOT a simple Male and Female polarity. In actuality, gender is a continuum, a spectrum between the poles of male and female , with an infinite number of possible states of being in between. Even the most polarized individual still contains elements of the 'opposite' gender within their construction and expression.