Turns out my father fucked her father
Turns out my father fucked her father and got herpes. On the way to the hospital for a check up his taxi gets into a car accident and he realizes that the guilty driver is his old highschool bully. In a fit of rage and righteous vengeance he leaves the taxi driver, seduces the bully and gives him herpes too. So then the bully senses something is wrong and goes to the hospital for a check up where he finds out he has herpes. But turns out that he and my wife's father are fuck buddies and bully knows about his herpes condition which is why they always use condoms. There however was one time when they were near black out drunk and don't remember if they used a condom, so the bully goes to my wife's father to have a confrontation which ends in both of them getting fatally injured in a sicilian knife fight. So my father realizes what happened and goes to their joint gay funeral only to see his taxi driver who turns out to be my wife's grandfather or her father's father. Then the grandfather who had observed the seduction connects the dots, gets an axe and goes to my father's house for a revenge. But my father had already predicted that, so he mines his own house with explosives home alone style. What he doesn't yet know however is that the guy he bought the explosives from had a part time job at the hospital's std ward. He remembers the two distinct herpes cases one of which ended in tragedy and suspects that something might be going on too. He also has a part time job as a photo journalist for the local news magazine, so he follows my father and inspects his house where he meets my wife's grandfather and recognizes him as one of his earlier patients.
"Hey, Winston, how them herpes treating ya?" he says. And suddenly everything clicks in Winston's head. If he hadn't fucked his son back in 1986 then his son wouldn't have had herpes and wouldn't have been able to give them to my father who wouldn't have been able to give them to the school bully and the tragedy wouldn't have happened. His old guilt pops up and now he also realizes that he is indirectly responsible for his son's death, probably to an even larger degree than my father. In a psychotic break he performs a variation of seppuku using the axe. After witnessing all of these events my father sinks deeper into alcoholism and two months later dies in a house fire caused by burnt burittos. So, yeah, me and my wife, we just kinda bonded after that.