This is one of my favorite parenting subjects.
Teachers often know their students better than some parents do.
I also spent many years teaching in the public schools and saw the very same thing. What I have found quite often is that a child will take on his parent's emotional states, as well as personality, feelings and quirks. A child could have a fairly calm youth, with no major crises to deal with, yet still grow up with low self-esteem, anxiety or other emotional challenges. If that parent sat around and felt slighted by life and felt that everyone was against him, the child might incorporate these feelings. When I was a teacher, I saw some very bright and gifted students who seemed to have the world on a platter, yet were quite down and depressed.