Why Children Are Different?
Two children come to mind.
Once I was invited to a party. There were many people, including families with children: some kind of celebration was going to take place.
I was sitting on a sofa. A baby climbed onto the sofa, crawled up to me and kissed me on my cheek — so sincerely, strongly! He poured his love all over me! He kissed me with such a cordial love! If I had not been familiar with his biography, I would have thought that he was a student of our School, because I had never seen such children outside of our School!
And I knew another child. I met him several times in the streets of Saint Petersburg. He was probably five years old. His eyes had a look of hatred — eerie, piercing look of hatred for everything and everyone. Moreover, this look and this demonic state were inherent in him.
I met him for the first time when he was stealing a hat from one of his peers. Our eyes met; he flooded me with his hatred — and ran away.
Second time I saw him scratching someone's car with his knife. Again our eyes met, and again it was the same hatred — and again he ran away.
These are two extremes.
I heard the idea that all children are little angels, that we must become like children and so on. Like what children?
When Jesus said “become like children”, He meant the very specific quality of the best children — “openness of the soul”; this is clear both from the context of the New Testament’s Gospels (Matt 18:3, Mark 10:15; Luke 18:17) and from apocryphal Gospels. He called His listeners “to open”, “to undress” themselves as souls before each other and before God — in emotional love!
Jesus meant good, gentle, sincere children. Some children, however, are malicious, rude, extremely egoistic, deceitful, looking at other people as caged wild animals look.
Why are children so different?
Materialistic science has been studying this problem for decades. Different scientists, depending on the profile of their work, emphasize different factors that influence the psychic development of children.
Geneticists talk about the role of genes, that the character traits are allegedly transmitted by genes in the same way as the color of the eyes and hair, or other body characteristics.
Embryologists, obstetricians, and perinatologists look for the cause in how the formation of the brain structures of the fetus was influenced by hormones, mother's stress, hypoxia, birth traumas, and various intoxications.
Psychologists and psychiatrists address various social factors, primarily the character of the child’s contact with the mother at certain “critical” stages of its development. For example, it has been clearly demonstrated in the studies of children as well as in experiments on animals that a lack of harmony in the relationships with the mother at a certain age leads to excessive aggressiveness in the later years. Additionally, the social disorders may be caused by a lack of adequate contact with peers during childhood. 
Commenting on this, I want to note that all these factors indeed play a certain role.
Genetic influences may take place — through genetically determined features of the development and functioning of the hypothalamus-hypophysis-adrenal system. If this system can produce and release into the blood more of adrenaline and noradrenaline, such organisms turn out to be more active in regular and extreme conditions. It may also create a certain predisposition (not predetermination) to excessively aggressive character traits.
And, of course, different factors causing damage to the fetus can lead to distortions in the development of different areas of the brain and endocrine glands, thus affecting one’s emotional characteristics in adulthood in different ways.
Different brain structures, responsible for different functions, are formed during embryogenesis at different times, and every one of them is most vulnerable to damaging factors during this critical time of their formation. Therefore the same damaging factor applied to the fetus at different times of its development leads to formation of different distortions, which sometimes get manifested only in adulthood. [5-6]
The social factor also has a great importance in younger ages. For instance, if the child suffers negative emotional stresses due to separation from the mother or from the person who substitutes for her at the age from 6-7 months to 3 years — then in adulthood such a person manifests psychopathic traits, including excessive aggressiveness. Significant emotional and behavioral problems also occur because of the absence of adequate (that is, natural) contact with peers in childhood. 
Yet the most important reason for the difference between children is not known in the modern materialistic science. It consists in the fact that not only bodies are different but the embodied souls as well. After all, souls incarnated in children’s bodies have been “adults” before; the majority of them — many times. They come with character traits and other characteristics developed in their past history.
This applies not only to human beings but also to animals. And this explains why in experiments on animals as well as in human studies the same damaging influence does not lead to the same result for different species.
Imagine, for example, two persons. One of them in the past life was already holy, and the other one was diabolic. The same high level of adrenal hormones in present bodies will have the opposite effect on them. The first person will more intensely devote himself or herself to spiritual service; the other one with the same vigor will commit robbery and murder.
Besides that, we should remember that incarnation into bodies of different physical qualities is determined by God. Therefore, there is no “bad luck”, since God plans and carries out everything in such a way that the embodied soul is given the best opportunities for its further improvement.
One may ask: can maimed and ugly bodies help someone in self-development? The answer is yes. For example, if someone who in the past life reveled in power, was cruel towards others and maimed their bodies — it will be appropriate that such a person suffer himself or herself in order to realize what pain and suffering are, and through this learn compassion for others.
Concerning the incarnations of wicked people — villains are needed for ensuring the diversity of the life situations, so that we may better understand the psychology of each other. Their fate is further degradation to the very bottom, until some of them change and there, on the bottom, in their suffering, begin to search for the way out to the Light.
Now let us consider another factor affecting the development of children — their upbringing. It is the most relevant factor to analyze in spiritual schools working with children.
I remember one day I observed the following scene: a father — well dressed, arrogantly self-confident man of athletic build, of about 50 years old — was giving “life lessons” to his daughter of 10 years old. They stood in a park, and the father, pointing to the passing people, “explained” to the daughter about every one of them: this one is a scoundrel, that one is a bastard. The poor girl listened to him attentively and probably for many years learned father's “lessons” of hatred. Only at the age of 20 many people (not everyone) manifest the ability to seriously re-evaluate everything that adults taught them earlier.
Dedicated education can be either very harmful or very helpful to children. They can be taught, for example, contemptuous disdain and hatred for everything or, on the contrary, they can be taught to love everything living, taught that love and harmony are good and that God wants us to become like this, etc.
The correct education of children is the most important factor of the spiritual help to people, the most worthy and interesting kind of spiritual service.
This is also a way of self-development in active love and intellectual creativity.
* * *
Let's look once again at the main principles of spiritual education of children.
The first principle is active cultivation of the ideas of love (for this is the main thing that God wants from us!) followed by the principle of broadening children's horizons. We must introduce into children's memory different programs of the ways they can live having grown up. We have to show them that there are chess, temples of different religions, nature which we can and must love, there are methods of tempering the body, the possibility of expressing oneself through painting, music, dance, photography, different kinds of sports, and very interesting and different ways of getting education, and that all of this can be used for serving other people, as a way of giving them our love.
Education also can be given by an example of deeds of adults, when children in the relaxed atmosphere witness the events in the spiritual school where their parents study. Alternatively, it can be done by arranging special classes and sections for children of different ages.
At the same time, it is necessary to remember that there are problems inaccessible to children's thinking. For example, the information about the existence of unembodied forms of life should be presented to them in such a form and in that volume which do not lead to formation of mystic fear. Mystic fear can become a basis for development of serious psychopathologies, which prevent a child’s development.
Also, one must not teach children profound meditative techniques, otherwise they may “get lost”, lose adequate contact with the material plane. We need to remember that everyone must develop themselves first in the material world, and only then they will be able to walk the serious religious Path successfully and safely.
It is also necessary to protect children in every possible way against attempts of different ignorant mystics to involve them into contacts with the beings of the astral plane under the guise of spiritualism, into a dialog with “extraterrestrials” and so on, as well as against attempts to engage children in magical and occult experiments. Participation of both children and adults in such actions is a direct way to development of serious mental pathologies in them.
It is also very important to teach children to think, provoking them to do it, for example, in such situations as solving the problem of crossing a forest brook, building a fire so that it does not cause much harm to living creatures, etc.
Or one can ask children questions like “why?” — so that they learn to find answers themselves rather than receive them from adults, and so on.
During communication of children between themselves in the group, the instructor should benevolently but firmly stop all manifestations of vicious tendencies, such as aggressiveness, propensity to take someone else's things, even the most trifling. Children can remember well, for example, such formulas as: “Jesus Christ taught, that you shouldn’t do to anyone what you don’t want be done to yourself!”, or “The one who takes without permission anything that belongs to someone else is a thief. And a thief is a very bad person!”, or “In the very good book called the New Testament it is written: love each other tenderly with brotherly love! And what you have done — does it look like tenderness?”
Some simple meditative exercises can be of great educational value. For example, all children can imagine a little sun in the chest and then run around and shine at each other with visualized sunlight.