I also think this is a very interesting topic. My understanding is that a person’s nature is a combination of three factors.
1. The Condition of the Subtle Body
2. Genetic Makeup
3. Environmental Influence
The body one receives at the time of birth is a direct result of one’s previous activities; practically speaking ‘material body’ is synonymous with ‘karma’. It is also said that one’s allotment of happiness and distress is already determined at the time of birth. At birth there are two factors determining a person’s makeup, i.e. factor 1 and 2. It is definite that one inherits qualities through genetics; I have heard it said many times and in my experience I have seen it to be the case that the female child will generally inherit the qualities of the Father, while the male child generally inherits the qualities of the Mother. The subtle body, composed of mind, intelligence and false ego, contains many impressions (samskaras) from previous lives. These manifest as desire and hate – lust and its flipside. Sometimes it is found that some children are naturally inclined toward a particular activity and yet for others the same activity can be like poison. Gauracandra gave the example of some kids who can sit quietly in one spot whereas others are just too restless. It’s difficult to say which qualities are the results of which factor; I can only think that the arrangement is perfect. One’s new gross body will be a perfect match for the condition of one’s subtle body as dictated by the laws of karma.
The single biggest factor determining a person’s makeup, especially in areas of ethics and morality, is one’s up bringing. Environmental factors during childhood have a huge effect on the adult psyche. Practically speaking an upbringing is a process by which one inherits the intelligence, or lack of intelligence, from one’s elders. Intelligence is the faculty with which we discriminate between right and wrong. Therefore the possession of intelligence equates with the possession of virtue. When we think of intelligence we think of advancement in knowledge. Knowledge, as described in the Bhagavad-gita, depends upon goodness (sattva-guna). We find that those who are advanced in material knowledge like to think of themselves as intelligent. But as long as they are engaged in sinful activity their so-called advancement in knowledge is simply advancement in ignorance.
So it is the duty of the parents to teach the child virtue. This is done in two ways, by instruction and by example. Childhood is the training ground for adult life and therefore childhood should be the time we learn what is the purpose of life and what is the nature of this world. Prabhupada described that there are basically four classes of intelligence. For a child with first class intelligence you can explain to him, “Don’t touch fire, if you do it will cause you pain” This instruction will be enough for him to learn not to touch fire. A child with second-class intelligence even after hearing this instruction requires seeing the result of touching fire, upon seeing another child burn his finger he then learns not to touch hot flames. A child with third-class intelligence, after hearing the instruction and seeing another child burn himself, still doesn’t understand that fire burns, thus he has to himself put his finger in the flame in order to associate fire with pain. A child with fourth-class intelligence will repeatedly put his hand into the fire and not learn that it is wrong even after repeated burns. I would say that one’s capacity to fit into one of these classes is due to karma. It is not that of the first three classes one will necessarily become more virtuous than the other, as that depends on what lessons are being taught, it just means that the children will learn differently, but they learn nonetheless. I would also say that in different areas of interest an individual will display sometimes first class intelligence and sometimes third class intelligence. For example children usually learn quickly not to cross the road without looking left – right – left again and listening for cars. But the same child may take quite a bit longer to learn that eating sugar candy is bad for you as it rots your teeth.
Discipline must be enforced upon children, as I previously mentioned childhood is the training ground for adult life, and as we know adult life is not all fun and games, and therefore children should be taught the seriousness of life. This seriousness means that for every action there is either a punishment or reward. Sometimes a stick is needed to reinforce valuable instructions upon a naughty child; in fact to not use corporal punishment when it is necessary is something I would consider as child abuse. If the child acts sinfully and gets away with it due to his parents apathy for strict discipline then he will grow up with a misconception of the nature of life. In adult life if we perform a sinful action then we will reap the result in due course. This result is like the whipping stick of maya. It is essential the child learn about such reactions from his loving parents prior to being released into the ‘real world’.
“Humility; pridelessness; non-violence; tolerance; simplicity; approaching a bona fide spiritual master; cleanliness; steadiness; self-control; renunciation of the objects of sense gratification; absence of false ego; the perception of the evil of birth, death, old age and disease; detachment; freedom from entanglement with children, wife, home and the rest; even-mindedness amid pleasant and unpleasant events; constant and unalloyed devotion to Me; aspiring to live in a solitary place; detachment from the general mass of people; accepting the importance of self-realization; and philosophical search for the Absolute Truth -- all these I declare to be knowledge, and besides this whatever there may be is ignorance.” (Bg 13.8-12)
Krishna here declares these virtues as knowledge. The greatest virtue in this list that must be taught by instruction and example is “constant and unalloyed devotion to Me.” I believe that if we cultivate this virtue especially then the rest will follow. There are many lists of divine qualities throughout the Vaisnava scriptures; we should know them well if we expect to be able to teach them to our children. I think moral tales are fantastic; the Mahabharata and Ramayana are especially wonderful, but all fairy tales teaching divine character can be read to children.
I hope that sheds some light on the subject.