You think you’ve heard all about plots? Well, there’s this novel “‘—All You Zombies—’“ by Robert A. Heinlein. Apart from such a catchy title, it’s about a few time travel paradoxes, including being tricked into impregnate his younger female self, before having a change of sex, basically becoming his own mother and father. So what would make it more unusual? I won’t spoil the party yet, in case you want to read the short story by yourself.