I was more so meaning the choice between which term you wish to use to refer to yourself. If your nature is to be a slave, then you will no more be able to change that than change the weather. If you deny it for too long it becomes an aching hunger than burns with the fury of one thousand suns.
Switches are a variable between the slave/submissive/subordinate and the Physical/Mental/Verbal. They are still fundamentally based on these categories, but they utilize more of them then the average bear. Again, a switch chooses which category to refer to themselves as, and the basic principle behind my initial post is still valid even for them. ;D
The choice of which term we use to define ourselves as a bottom or as a top will determine how others of the opposite end of the equation will view us. That's why we must take care to choose the truthful one, as oppose to the one we want to be true.