I have noticed that sometimes one particular child in a family has a blank check, with no limits. The only child, or an only girl or an only boy, or the baby in the family, or a youngster who has been sick a lot - anyone of these can be the one who is never reined in. They are not really thinking about their youngster right now, today's child in this very year. They vow they will not do that to their child. The result is that now they value freedom and leeway more than is good for their boy or girl.
Some parents go overboard by being softies and easy-marks.
I have seen as many parents who are too tough and who, I think, expect too much. I am sure their children feel as if their mothers and fathers are angry with them most of the time. Their children must feet that they never do anything right, that they are always a disappointment. It is hard to strike a balance. Yet the path to good discipline lies in finding the right mixture.