Cain from Nowhere (1970)

Cain has been traveling for a long time throughout Europe. Back "home" he knocks at the door of his parents' trailer only to be rejected by his hateful mother, who once again blames him for his laziness and once again compares him to his brother Abel, a successful businessman and a right guy, good to his parents and stuff. As for his father, now blind and crippled, he escapes his wife by being permanently drunk and he is of no help. In disgust, Cain runs away from the place and contacts Abel, the perfect son, to borrow money from him. But, although Abel tells him he doesn't mind helping him, Cain shoots him down with a gun found in his brother's car...