To Age or Not To Age, That is the Question

My good friend Gemma Halliday posted a question on Romance Divas yesterday, and it got me thinking.

If you're reading a YA series, do you expect the characters to grow up?

JK Rowling did it in her Harry Potter series, of course, which correlated nicely with how her original readers were aging. But that was a fantasy world, and the characters were dealing with fantasy issues very far removed from our own everyday world.

For a contemporary, if the main character is 16 in the first book, would you expect her to be in college by the end of the series? Is this a good idea?

On the one hand, if you're putting out 1 book a year, and your target audience starts out in the 12-15 age group, then by the time you're 3 or 4 books in, your readership has "outgrown" this type of book, so aging your character might be a good idea.

On the other hand, what about your readers who find you once you already have a backlist? As a mom, would you want your 12-year-old daughter to start off reading books with a 16-year-old protagonist and then continue reading that series all in a row, even if the main character is now in college? It wouldn't be a big deal if your daughter is now 16 or 17, of course, but if she came upon the entire series while she's a preteen, it could get awkward.

But then again, keeping your main character in a vaccuum and never aging her, Nancy Drew style, is unrealistic.

YA writers...what do you do?

YA readers...what do you prefer?