There are two groups of people who are teaching without certificate or often even without any formal training. They are university professors and parents. It is true that professors poor at teaching deter the learning process of their students, but their negative pedagogic effect cannot be compared to that of those parents who do not (know how to) educate their own children.
In my opinion there are two kinds of people who are not supposed to be parents: firstly, those who cannot feed their own children; secondly, those who do not (know how to) educate them. Unfortunately, we see here in Israel quite a few people who beg on the street or by visiting our houses for money to buy foods for themselves and their children. From time to time I give money to those in other situations of distress, but I find it difficult to have mercy on people who have brought new lives to this world without securing first their most fundamental physical needs. The consolation is that these children often learn an important lesson of life from their parents.
The negative effect of the second type of parents is far more pervasive. They need parental education (education to become parents) before parental education (education of their children as parents). In many cases they also need education to become social beings before becoming parents. Their guiding principle of their life is often egoism with no attention to others around them. They are sometimes even unaware that their egocentric behaviors bother others, and when they are complained about, they never apologize. It would not be difficult to imagine what kind of children they have. This is a vicious circle. I am sure that the parents of these egocentric parents were also like them. In my opinion many of the interpersonal problems in society are causes by those "educated" by these unsocial, if not antisocial, parents.
Is there a way to put an end to this vicious circle? Unfortunately, I do not think so. The only possible action we can do I can think of is to explain to them rationally how detrimental the (un)social values they are transferring to their children directly or indirectly, and they are not acceptable in any civilized society. One of the nightmares of life is to have such people as our neighbors. It is not always easy to remain rational with these people, who often seem as if they had escaped from a zoo not long time ago.