Good for you.Filling out a form is literally how sex is assigned at birth by the doctor. Your comments and links about fetal development, especially the statement about all fetuses starting out female, are explicitly about fetal brain development. And, yes, I have been teaching at the university level for more than 20 years, starting with physiological psychology and a neuroanatomy lab way back in the day at FSU.
Its not assigning its marking what's already decided. The doctor cant write what they want like assigning a work detail or a shift. The sex is decided the doctor merely transcribes information. Does the doctor assign a weight and mother and father too?