"A teacher affects eternity; he can never tell where his influence stops"
from "Tuesdays with Morrie" for Mitch Albom, 1997- an old man, a young man and life's greatest lesson
A teacher could easily take over the role of parents - up to a certain level. as you never forget your parents, as their effect never stops on you, and your children - so does the effect of a teacher, mentor, professor, etc.
they affect their students' lives in a scary way.
if you are one of them, just be careful of what image you give to your students. you are the row model they tend to follow.