Sentence:  Earlier this month J.K. Rowling posted some tips on her website. “I haven't got 10 rules that guarantee success, though I promise I'd share them if I did,” she wrote. “The truth is that I found success by stumbling off alone in a direction most people thought was a dead end, breaking all the 1990s <WSD>shibboleths</WSD> about children's books in the process.” 
Meaning of the word marked with <WSD> tags:  A common or longstanding belief, custom, or catchphrase associated with a particular group, especially one with little current meaning or truth.