This is another comment on balance. Like subject-verb agreements, so does the pronoun/antecedent need to agree. If the gender, quanity, or thing is not placed correctly it will throw off readers and confuse them, after all it is the same language that is being used. As such, if refernces are off the reader won't be sure what it is that is being refered and the reader will be confused. It is one of the core problems of good writing. ~ M. Nowell