Explain how it is that Oedipus’s problems with fate and the gods can be seen as essentially his own “fault”?

Explain how it is that Oedipus’s problems with fate and the gods can be seen as essentially his own “fault” or responsibility – since he didn’t know that he killed his own father or married and had children with his own mother. How does the play establish Oedipus’s own responsibility for his fate?