Rule about Underage Characters in Stories.

[Babypants]

It has been a long time since this thread was updated, so let me ask a question that hopefully will serve to bring a very interesting and informative conversation to more readers.

Let's start with generic or global descriptions as opposed to detailed ones.  For example, (1) can we have an adult character in dialogue reveal that he/she lost his/her virginity at, say, age 15?  (2) Can we have a minor brag about his/her sexual experience in global terms?  A typical piece bit of dialogue might read: "hey, come on, I lost my virginity when I was X."  Even more elliptical would be "hey, come on, I've been putting out since I was X."  Without global references, whether direct or metaphorical, our adult characters won't have a history that informs the thoughts, words and actions that we assign them in their adult roles.  

[DLClayMongoose]

Hypothetically, what if it were a slice-of-life story with an elementary-aged protagonist who still has a lot of “baby” in him/her that was never outgrown?