Sophocles, Oedipus Rex is in many ways about the concept of family. At the heart of the tragedy, Oedipus's parents leave him to be exposed in view of a prophecy that he would marry his mother and kill his father.
In the end, he is not exposed, but taken to another city, Corinth, where he grows up. However, while he was traveling, he did wind up killing his father and eventually marrying his mother. When he finds out his transgression, he blinds himself and Jocasta, his mother and wife kills herself. In view of this, we can say that all of this is a family ordeal. The whole action of the tragedy is to unfold this plot.
We also also say that the tragedy is about political responsiblity, because Oedipus as the leader of Thebes want to save it from the hardships of the plague that hits Thebes at the beginning of the work.