I get to teach genealogy on a regular basis. While I enjoy sharing the subject, I've started to appreciate something else more: student questions. I don't know everything, and my students' questions never cease t make me aware of that. I get questions about everything from the format of the Hartford Courant databases (yes, it is online) to the contents of the U.K. census. It's hard to admit you don't know everything, but this has become a great learning opportunity. I've delved into subjects I never would have covered.
My lesson: take the opportunity to teach. Share your genealogy with your family. Write an article. You may find out what you don't know... but you'll learn.