Chip Heath and Dan Heath discuss the Curse of Knowledge in their book, Made to Stick. The fact that we know something makes it difficult for us to teach it to someone else who doesn't know it.
As they note, "When you open your mouth and communicate, without thinking about what's coming out of your mouth, you're speaking your native language: Expertese. But students don't speak Expertese."
In other words, being an expert in a discipline makes it hard for us to relate to others who are not experts. Read more about this in their article, Teaching that Sticks, and check out their blog for more free resources here.