If you want to summarize the changes in family structure over the past century, the truest thing to say is this: We’ve made life freer for individuals and more unstable for families. We’ve made life better for adults but worse for children. We’ve moved from big, interconnected, and extended families, which helped protect the most vulnerable people in society from the shocks of life, to smaller, detached nuclear families (a married couple and their children), which give the most privileged people in society room to maximize their talents and expand their options. The shift from bigger and interconnected extended families to smaller and detached nuclear families ultimately led to a familial system that liberates the rich and ravages the working-class and the poor.
That is from David Brooks writing in The Atlantic, do read the whole thing, so far the best essay of the year with many fine and subtle points.