It's the 12-year-old girl. I'm convinced we took her out of the crib too early. She's never slept by herself for any period of time. She's only been spending the night out the past year or so. Plus, they sit in there and watch MTV and talk. I like to read a book before bed.
My 7-year-old son goes to sleep easily. One of us reads a book to him and lay down for a bit. But, if I need to go do something, I can tell him goodnight and he says goodnight and goes to sleep.
It's frustrating because my daughter's starting that independent stage, but still whines about things like that. My wife gives in. Her stepmonster wasn't so kind, so I think my wife overcompensates.
That's the short analytical side of it.
EDIT: but I get the three cats!!!