There really is an old British folk song about the very subject: "Lang A-Growing," sung by Ewan MacColl, Liam Clancy and others. The final verse begins:
In his twelfth year he was a married man
And in his thirteenth he had gotten her a son...

So much for (A) The moral deterioration of these kids today and (B) A folk song yet to be written. It's been done.