why oedipus killed his father

Oedipus finds out he was adopted and consults the same Oracle who tells him the same thing save the part about his real birth parents. Not wanting to kill his dad, Oedipus travels to Thebes. On his way he encounters a travelling caravan. Both claim right of way on the path. There is some major road rage or rather path rage and Oedipus kills the man who turns out to be his birth father.