Word of the Day - "Cryptomnesia"

"Cryptomnesia, or inadvertent plagiarism, is a memory bias whereby a person falsely recalls generating a thought, an idea, a song, or a joke, when the thought was actually generated by someone else. In these cases, the person is not deliberately engaging in plagiarism, but is rather experiencing a memory as if it were a new inspiration."
- http://en.wikipedia.org/wiki/Cryptomnesia

I imagine this is rife in comedy writing. I've only been at it a while, and I've already had fits of debilitating paranoia when I think I've succumb.

Any thoughts from the old hands (or new) of the forum?

There's some old writer's adage that "genius steals, mediocrity borrows" - or perhaps it's the other way around.

A really good comedy writer may, to paraphrase The Beatles - "Take a bad joke and make it better".

I reckon I have only once deliberately used a line I read (in Viz actually) and used it as a basis of a line for a character.

If your sitcom is gag-lead then duplication of other people's jokes is more common than if your sitcom is character led, where you find the gags flow more naturally from your characters. (You are also less likely to inadvertently piss off stand-ups by this approach).