I originally had no interest in adopting any children because I figured it would be like getting married- the NPC just becomes an uninteresting wooden puppet that does the same predictable things over and over. They become a game mechanic instead of a character in a larger story. However, while running around Whiterun, I met Lucia and I felt sorry for her living alone and begging for money. She seemed sad up until I told her I would adopt her. Now she lives in Breezehome with myself and Ysolda and when she told me I could have anything out of her personal chest that I wanted, I immediately thought, "No, those are yours things." That's when I realized she wasn't just a game mechanic to me.