I think parents are more responsible for moral education of the child than teachers. Parents are the first people who are involved in the process of upbringing. Before school parents, or sometimes grandparents, not only take care of their children (grandchildren) but also teach them what they should or shouldn't do.
Parents give the children there tolerance and learning capality through birth by genes. That is Nature. Nuture does play a role in a students education, however is there is no action by the student, then all the parenting in the world could not make a change in whether or not a student could succeed. Success is based on a person's motivation to work hard and dedicate themselves to reaching their goals. Having a parent walking next to you everywhere telling you to work hard is not necessary. It may not even work.
I completely agree that success is based on a person's motivation to work hard and dedicate themselves to reaching their goals. But that is the question, who is responsible for stimulating this motivation. Every child (at least until this child reaches a definite age) respects his parents, follows their instructions, even copies their behaviour and view to life. That's why parents should pay attention to their lifestyle. Isn't it the first step in forming children's morality?