Some of the stuff you can make can definately pass for a late-teens character. If you're talking 13ish, then no.

But I'm sure that modders will accomodate all your hebephilic or ephebophilic needs.

You're on the Internet.  Everything you say will be automatically evaluated in relation to sex.

On a serious note, it would actually be kinda cool to have young characters in the 13-15 range. It would almost become like a young adult fantasy like the Golden Compass everyone used to read. It's unfortunate that they'd then need to deal with hairy issues like child death.

Well, depending on how aging is done, I doubt you would stay a child for much longer than your first few turns. (like 10-20 turns, 100 turns at an extreme ... either way its still early game, with potential for child-bearing in your mid-late teens I suppose- if you get your dynasty started fairly early)

Now, if INSTEAD we are talking about a sovereign who stays as a child for the ENTIRE GAME, then i see that as a perfect reason to take it the wrong way

Can vampire child sovereigns have children? Male? Female?

Well, in modern times most races aren't fertile till age 14 or so (exceptions being 13 and 12, usually of african descent)

however I suppose in medieval times even Europeans might have been regularly fertile at 12/13? Or perhaps getting married before being fertile was a common enough practice.

In any case, many Middle Eastern (turkish?) cultures marry off their women as soon after their first period as possible. (probably different now?)

Interesting. Well, either way, there have been many different marriage customs.

Point is, that although I personally don't see a need for young sovereigns (as I don't think it fits the theme) I guess people can mod in their Narnia sims or what not.