How important is the concept of family to Oedipus the King?

The concept of family is developed through the idea of origins. Oedipus embarks upon a search for his own origins, and - though he does not realize it - for his real parents. As the child of his own wife, and thus father and brother to his children, Sophocles explores various interrelationships between where things began and who fathered who. Similarly, the play itself works backwards towards a revelatory start: the story has, in effect, already happened - and Oedipus is forced to discover his own history.