Up to the first half of the 20th century, western societies taught their children stories which illustrated and reinforced a particular conception of marriage and family; the same conception was supported by the civil law, by social expectations and social sanctions; and the same model was experienced by the vast majority of people. The same is true of the conception of the role of the state, the place of religion in society, gender roles, and a thousand other things. These shared understandings, which took on distinct flavors in different countries and in different cultural and ethnic groups, were the basis of a sense of solidarity.
One does not have to imagine that the culture of any particular time and place was perfect in every way, in order to realize that a society which lacks a culture in this sense is in serious trouble. But that is our situation today. The old models of how to live have not entirely gone away, but they are no longer supported by a social consensus. Our children are continually exposed to mixed messages, and civil law and social norms not only fail to support the old model, but in many ways work to undermine it. On the other hand, that model has not been replaced by a consistently applied, widely understood, and coherent, alternative.