Which of the following statements is mentioned in the passage?

Great changes have been made in family life because of science and industry. In the past, when more Americans lived on farms, the typical family had many children. In a family, parents and their children often lived with grandparents. Often, too, uncles and aunts lived nearby. But when industry become more important than agriculture in American life, families became smaller because industry requires workers who are ready and able to move off and to move again whenever necessary. In the future, because of industrialization, a typical family will be required to move even more often than now, so families will be even smaller. The typical family may remain childless and consist only of a man and a woman. A small number of families may take raising children as their chief work. At the same time they may also raise other people’ s children, leaving those families free to move from job to job.