The first teacher we have in our lives in most cases are our parents. They teach us to walk, to speak, to eat and to have good manners before we go out to "The Real World".
They are involved in the development and education of a children more than a professional teacher.
During the initial stage of life when a children is born, parents are the first person whom they have to interact. Parents are very committed for the growth of their children.
They give most of their time and energy for the children to make them learn new things. They play with their children, teach them netiquettes and manners and how to interact with the society.Parents always try to give them the right knowledge and in right direction. Even before a child interacts with professional teacher in school, parents teach them a lot of things with the full dedication and commitment, giving them proper time, which a professional teacher cannot give.
During second stage of child development, adolescence, parents are still give their best advice, but children may not accept it. Adolescents are notoriously rebellious in many cases and they may automatically reject their parents advice. At this stage of life, children's friends are their best teachers. They can quickly follow their friend's advice rather than their parents advice which in some cases can even be same. So , at this stage of life parents should give their children some space and they also need to be very patient.
On the other hand,I would say that parents are not professional teachers and they tend to be very biased by their love of their children. So, wishing easy life and good things can prevent their children from maturation. Also, parents can just provide single viewpoint of the world, while good teaching should be based on different attitudes. Also with time, parents become little conservative and children needs to be
So in conclusion, while parents are not the ideal teachers and a well-rounded children need great diversity of teachers in their lives, in order to have a accurate viewpoint of the world, parents are generally the most committed of all the teachers and have the greatest emotional investment in their children and their future.