.  When I rewatched Season 0, there was an episode when they were all talking about not knowing everything about each other and Izzie was carefree and laughing saying there were no skeletons in her closet or something like that but then this season we find out she has a daughter she gave up for adoption. I wonder if the writers developed that story as an afterthought to give the character more dimension instead of just the model-doctor because usually when someone says they have no secrets, there's at least a hint that they're lying or a nervous laugh. But the way Izzie said it, she really sounded like someone that didn't have a care in the world and with no tell-tale facial gestures to the contrary.  