I have a cousin, well two really, who were adopted from Mexico, a brother and sister (different biological parents that is, but adopted into the same family).
One day when he was 5 I believe, and understood that he was adopted, he asked my aunt why his mother put him up for adoption. Aunt told him "Well your mother loved you very much, but she couldn't afford to take care of you so she took you to the orphanage so you could be adopted by someone who could take care of you."
Well cousin thought a moment and said "Well, can we go to Mexico, find her and give her money so she won't be poor anymore?"