All behaviors linked to gene instructions have an evolutionary reason to exist. They gave an advantage to survival and reproduction and over thousands of generations become infused into the human genome. What advantage is there to males pretending to be females remembering that there is no way a male in a natural environment could ever fool another person. There is no "passing" in the jungle.
Until very recently life was short and brutal, most people did not live long enough to successfully reproduce. The traditional behavior of males being competitive, protectors and providers is the behavior that females do seek because it increases the chance of successfully raising offspring.
And if you believe CD behavior did ever occur in our evolutionary past then there must have been a time when all males pretended to be females for this code to be inserted into genome. This also means all males carry this behavioral sequence in their genes.
Indeed but all cells in the brain like the rest of the body do eventually die. There is not a single cell in your brain that has survived from the time you were a baby. They have all been replaced.But the brain, like the rest of the body goes through stages of growth and development, it's not a steady-state but one of bursts. And there is only so much regrowth. Only some who suffer substantial brain damage are lucky enough to have their brains rewire around the damagedd sections so that other brain parts can take over the role of the dmaged areas.
Behaviors are based upon the linkage between cells. These linkages grow and become increasingly more permanent the more often we carry out the behavior. This is why as adults our CD behavior seems so intrinsic. But the average CD does not emerge until between the ages of 8-12 often without any previous experience of desiring to be female. This indicates that CDing begins more out of curiosity and experimentation which leads the child to learn that it enjoys the feelings which then progresses to an entrenched behavior. There are no doubt factors in the child's life that may push or pull the child to experiment - the belief that girls have it easier, the desire to creatively dress up, the desire to avoid growing up into an adult male, the desire to avoid responsibility, the desire to be quiet and submissive etc. The child finds adopting the opposite gender role satisfies parts of his personality that were being ignored by adhering to the strict male gender role.
Behaviors are not linked to genetic code. In my primary class at school there were identical twins (who are genetic clones of each other). But these twins had completely different personalities, almost the polar opposite of each other. If genetic code could determine personality then this event could not occur, the twins would have to have very, very similar personalities.