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 farm family, parents and their children often lived with grandparents. Often, too, uncles and aunts lived nearby. But when industry became more important than agriculture in American life, families became smaller because industry requires workers who are ready and able to move off the land and to move again whenever necessary. And large families can not be moved from place to place as smaller families can. So, at present people tend to have smaller families.
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 consists only of a man and a woman. A small number of families may take child raising 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.
The passage discusses influence of science and industry on American families.

A.T

B.F