Throughout my career as a teacher, I came across children who were totally lacking in confidence. They truly believed they could not learn (to read, do maths, play guitar). In most cases it was this belief that was hindering their progress. They had been told so often that they were no good, stupid, 'thick', losers - by their parents, teachers, so-called friends. Trying to unpick the harm that had been done and showing these children what they could achieve was a hard and lengthy task.
On meeting some of those children as adults, it became clear that the ones who had found someone who didn't constantly belittle their attempts gradually overcame some of the difficulties they had as children. But too many of them were damaged for life.
Education is meant to break the cycle of deprivation. It can't do that if the educators are the 'small people' and if the damaged parents are not involved in the process.