I've just been thinking (at work, as usual, and not about work) about a literary agent's site I researched recently. I won't say which as I intend to apply (because, apart from the point I am about to query, the agency looks superb). However, in the advice section, the writer suggests that we should read in the genre we write, ie:
If you want to write fantasy, read Harry Potter.
If you want to write erotica, read 50 shades.
If you want to write thrillers, read the Da Vinci Code.... etc.
And I started to wonder, are writers becoming commercial? Have books always been commerically driven, as in - Harry Potter has finished, we accept that, and very fine books they are. But encouraging people to write 'the next Harry Potter' seems a little.... exploitative? Exclusive? "Don't write what you want - write what we want to sell."
I accept that a book with no selling potential is heading straight for a recycle bin in the agency's back room. But I'd like to think that a book doesn't have to be called "Harry Potter's twin brother goes to Hogwarts" before it stands a chance.
I don't know if clone is the right word, but, I would say they are looking for books that can sit along side those titles as it will be what is familiar to readers as well as writers.
I regularly go and look at the titles of the books that are in the genre I am writing for – I also read a lot of books in my genre too.
But as Jonathan says, you have to write what you want to read, common themes will run through any literature so that isn't a worry, but writing about Harry Potter's cousin going to Hogwarts isn't going to pass through the door either – unless J.K. Rowling's name is on it.
I am sure in my fantasy novel there are plenty of common themes running throughout, but I know there is also my world that I have created, my characters and creatures that aren't in any other book, and it's those characters/creatures that I enjoy writing about.
Maybe they're looking for clones, but I think mostly they're suggesting styles of particular genre that have an proven audience.
Because I write military Peninsular War fiction I deliberately stay away from reading that conflict but do take a look at other military HF. Inadvertant plagiarism could be an issue, particularly when mixing fiction into accepted (ish) fact.
So, maybe I end up with 'Sharpe on horseback', 'Flashman without the cowardice' or 'Hervey with attitude'. I don't think there's a problem with that: after all, Sherlock Holmes and Andy Dalziel are both detectives working with a partner but not many would consider the latter derivative.
If you don't write what you want to read there'd be no heart in it.