Trans women, also known as "mtf" (male to
female) or "Transgender
woman" is a man who regards himself as a
female (either privately or publicly).
The overwhelming cause for this state of mind as documented by the literature is Gender Dysphoria(GD)/Autogynephilic(AGP). Both are metal/sexual disorders characterized mainly by the view and feeling of oneself as a female.
GD and AGP are disorders known for making the sufferer feel like the other sex and therefore choosing to be present as a female is the a common treatment.