This is sort of what happens in the book version of "Wanted," instead of being part of an international ring of assassins, Wesley Gibson discovers his long-lost father was a supervillain called "The Killer," whose power is basically the ability to kill anyone with anything (this is where the "curving bullets" power actually comes from). And unlike in the movie, the book has a more tongue-in-cheek Clockwork Orange thing going on where Wesley can go on killing sprees and do whatever he wants with zero consequences. The big reason why it was changed (and why we haven't seen Nemesis on our screens despite that being a really simple sell "what if Batman decided to be the Joker instead?") is because it's really hard to root for a guy who's slaughtering people en masse. But this is presuming that the Zodiac KIller actually was this guy's father. What if he was lying? Why would someone lie about that? To get attention? As a weird way to meet women? To intimidate people (what a great way to stay out of trouble with fellow inmates, to be the son of an infamous serial killer)?

Interesting re Wanted. Re your last paragraph: Could be an interesting character study of someone who passionately believes his father was a famous heretofore unidentified serial killer. What sort of psych makeup does that character have, their underlying motivation? Or an author researching a book trying to figure out identity of serial killer. Gets sucked into lurid underworld of violence. Basically a great excuse to explore the 'shadow' aspect of character(s).

I may add a bit to it. A young man gets depressed when he finds his biological father to be a serial killer. He's under a lot of social hatred and oppression. His hope arise when a genetic doctor/engineer claims the killer isn't his father but his identical ( a cloned father). He was cloned by FBI for a special mission technically to spy on Iran's nuclear capabilities. His original father is a famous reporter on Iran-Russia region. When the cloned father comes to know the reality he abducts the young man (virtual son) to let his original father get killed and hence his survival. ( from FBI and for his-being)

I was immediately thinking comedy but it might be too close to "Hail To The King," this Marvel short film where Ben Kingsley is in jail and famous (remember how he was impersonating "The Mandarin" in Iron Man 3?). Well, he finds out that The Mandarin is real and not particularly happy about Trevor masquerading as him. It seems like they're going to follow up on that in one of the upcoming movies. I was also toying with the idea of Alternate History that you proposed the other day and had a wild thought: what if Hitler had two secret sons, twin brothers, each growing up on a different side of the Iron Curtain. And re: Wanted, here's where it gets even crazier: Wesley in the book is modeled after Eminem, gives you an idea of the attitude the book had going.

Dumb Story Idea #12 First Knight meets Punchline--King Arthur rules Camelot and makes the jester teach him to be a comedian while Guinevere falls for Lancelot. Feel free to check out all the @DumbStoryIdeas on Twitter .