It is not surprising, therefore, that the increased inequality in incomes in the United States since the mid-seventies has been caused in good part by larger returns to schooling and other training, and that many countries, like Mexico and Brazil, have major pockets of poverty related to regional disparities in opportunities for education. One has to start with the family. It is the foundation of a good society and of economic success. Families have differed over time, but they are still very important in the modern economy. To understand human capital, you have to go back to the family, because it is families that are concerned about their children and try, with whatever resources they have, to promote their children's education and values.
Families make a variety of decisions.
One is whether to have many children or to have fewer children and to try to do more for each child. As countries develop, the trend shifts very strongly toward the latter. Every nation that has developed has done that, some in remarkably short periods of time. Taiwan, for example, has a birth rate lower than the United States. Declining birth rates also characterize Hong Kong, Mexico, and Poland.