Two scientists at the University of Waterloo decided to explore the role that self-justification plays in parental beliefs about their choice to have and raise children: "In an earlier time, kids actually had economic value; they worked on farms or brought home paychecks, and they didn’t cost that much. Not coincidentally, emotional relationships between parents and children were less affectionate back then. As the value of children has diminished, and the costs have escalated, the belief that parenthood is emotionally rewarding has gained currency. In that sense, the myth of parental joy is a modern psychological phenomenon."