Every writer has gotten the advice to ‘write what you know’. It was my first bit of writing advice too. I believe there are two scenarios to look at when discussing ‘writing what you know’. Firstly, authenticity. Secondly, the limits of your imagination.
Authenticity is paramount to my decisions about taking on authors. The authentic voice that doesn’t seem forced, that seems effortless (but requires extensive effort to create) paired with natural dialogue is what lets you leap into the book with the characters. This authenticity often comes from knowing what you are writing from either having lived it or being closely connected to it.
However, career writers should be able to write about any location or type of character and make it authentic. The best compliment an author can get is a review that proclaims the writer must have lived in the location of the book setting to get such prolific accuracies of culture, voice, and characters when actually, they had never been there at all! This is the gift of imagination paired with extensive research. For example, the amazingly talented Helen Dunmore’s critically acclaimed pair of novels The Siege and The Betrayal set in Leningrad from 1941-53 were pure research that ‘grew from a lifelong love of Russian history, culture and literature’.