I once worked at Tutoring Club. My custom was to get there before the client arrived and sharpen the pencils ready for use. Any time I had to use a blunt pencil, I felt my mood decline. Interestingly, the owner of the Tutoring Shop took over the tradition and would sharpen the pencils before my arrival.
Long and behold, a few years later, our 9 year old son has the same habit. He will sharpen his pencil a couple times while completing his homework. I know I did not teach him that. He picked up the habit by himself. I have started to encourage him to use mechanical pencils to minimize the trips to the sharpener.
I guess the apple does not fall far from the tree! Can you think of a similar instance?