It runs in the family, the family is happy, and the sunset is red.

It runs in a happy family, and the sunset is the beginning of the narrative: a family composed of grandparents, parents and grandchildren is very happy, and it is interesting for a family to live together. In the twilight of life, we can also talk about the past.

A general term for a family composed of three generations: grandparents, fathers and grandchildren.

Family happiness refers to family happiness between the older generation and the younger generation who are related by blood.