I adopted just this past couple of days the flower girl in Windhelm and the homeless boy in Dawnstar. They're pretty thankful and rarely talk back, the flower girl has whined a bit here and there about not wanting to do what I told her to do but I believe that's just the standard convos programmed. It's not THAT bad since you're not the one feeding them and taking absolute care of them however you should get some children's clothes, dolls, and/or wooden swords (stolen or not) and give it to them to get the gift of charity bonus.