Incest is taboo because of genetic defects that can arise from it. That taboo predates capitalism you moron.
And Oedipus didn't realise Jocasta was his mother because his parents abandoned him with a pin through the ankles due to prophecy. Thus he never grew up around her. When they both realise the truth, she commits suicide and he blinds himself.
History and mythology are something else incels fail at.