Jane Austen and Regency enthusiasts might recognize Beau Nash's rules of conduct for one's time in Bath, which among other things declared:
. . . that the elder ladies and children [must] be content with a second bench at a ball, as being past or not [yet] come to perfection.
When I came across this quote, it struck me as being true in books nowadays. It is rare that I come across a protagonist older than thirty, but then again, I read a lot of historical. If you were lucky, you were married by sixteen.
So, is this just my preferred genre, or are the majority protagonists young?