There was a few hints in the game that Chell was actually the daughter of Caroline and Cave - One of the hint's being the 'Bring Your Daughter to work day' room

http://img23.imageshack.us/img23/1467/96166236.jpg

The turret opera, when translated says this

My beautiful dear, my darling beauty!
My baby, oh heavens
That admire her!
That admire her!
Oh my dear, farewell!

My dear child...
Why don't you walk away?
So far, away from Science!
My dear, dear baby...
Ah, my beauty!
Ah, my dear!
Ah, my dear!
Ah, my little girl!
Oh my dearest one!

Which raises a few questions xD

I never actually knew about any of that, especially the bring your daughter to work day thing. :shocked:

And I can see how that'll raise a fair few questions!! xD I'm guessing GLaDOS must've kept Caroline then in secret. Maybe in the next game she'll send the test subjects out of the facility to go and find Chell? :amazed:

At least for Chell