Body parts

We have lived in our secret dimension for centuries, cowardly if you ask me. We are neither boy or girl, we are both,since birth. On the eve of our 20th birthday we are put through multiple physical and mental evaluations to see which gender we was meant to become. Our directors refer to us as 'it's' but a few who are confident with what they will become demand a he\she title. On our 20th birthday also known as 'transition holiday' We are told in the procedure room what we will wake up as, as they surgically make us either a amazing man or a amazing woman and only then are we allowed to enter the dimension of humanity and never return to our previous life, if you can call it that. Of course we won't want to, we won't remember any of it. Only what they want us to remember