Complex sentence: The Joker has facial scars roughly in the shape of a smile, and he tells two stories about how he acquired the two scars on his face: parental abuse and self-mutilation, but it is unclear if either is true.
Split into simpler sentences: The Joker has facial scars roughly in the shape of a smile. He tells two stories about how he acquired the two scars on his face (parental abuse and self-mutilation), but it is unclear if either is true.