I think depending on the social and historical situation a name can have a big effect on choosing a book. I am sure there are still parts of the world where it is not encouraged to use a particular name in publishing your work to make it more acceptable. It may be harder to understand somewhere more multicultural and democratic, such as London for example, where all sorts of surnames pop up on the store shelves, especially as so many books are translated to English from other countries. But as the J.K Rowling case stated above shows, even still these issues, such as gender preference, arise. I have to admit, having a look at my shelf now, that most of my romance novels are by women authors and my thrillers by men although my poetry collection and text books are evenly mixed; I guess we all have our preferences and selection criteria, even if we are not fully aware of it.