orn this kind of person [toiosde ekphys]’) to the search for origins, his determination in this endeavour is in reality newfound; it has been forced upon him in the course of the investigation that he is undertaking into the murder of Laius.
No - it begins when he is told by the drunk that he is not his father's son (plastos)? I.e. that opens up a space of questioning, some interval in certainty about parentage, that requires answers...