Is Marty McFly the Worst Son in Fiction
In the original BTTF, he goes back in time and sets up a series of events that almost gets his mother raped by Biff.
And in this film, his greed contrives a situation where his mom ends up married to the said would-be rapist (not to mention, his old man is dead, his brother is in prison, and his sister is a step away from being in prison herself, although I don't know what for, unless Biff was able to change the law regarding the penalties for defaulting on a debt).