That's advice from Bret Anthony Johnston in the Atlantic's annual fiction issue.
I guess this issue has been on my mind lately (see posts below).
Here's a quote from the Johnston's article:
"I don't know the origin of the 'write what you know' logic. A lot of folks attribute it to Hemingway, but what I find is his having said this: 'From all things that you know and all those you cannot know, you make something through your invention that is not a representation but a whole new thing truer than anything true and alive.' If this is the logic’s origin, then maybe what’s happened is akin to that old game called Telephone... A similar transmission problem undermines the logic of writing what you know and, ironically, Hemingway may have been arguing against it all along. The very act of committing an experience to the page is necessarily an act of reduction, and regardless of craft or skill, vision or voice, the result is a story beholden to and inevitably eclipsed by source material."
The novel I'm working on is not autobiographical. But the place where it's set is where I'm from. Sort of...