There are three reasons for the formation of personality:
(1) natural factors;
(2) Early family relations;
(3) Great changes and psychological trauma.
About natural factors.
Most obviously, identical twins show different personalities when they are young. Because it cannot be changed, it will not be discussed in detail.
About early family relationships.
At first, the relationship between baby and mother, including eye contact, timely response to baby's needs, mother's patience and friendliness, and other very trivial behaviors, will affect baby's initial understanding of the world.
Around the age of two, children begin to explore more. At this time, fathers, brothers and sisters, pets and so on will all participate in children's cognition.
By the age of six or seven, a person's personality is basically stereotyped, and his inner security and psychological defense mechanism have been established.
Therefore, it seems a bit pessimistic to look at the old at the age of three and look at the old at the age of seven, but it is true from the formation of personality.
These experiences, experiences and cognition in childhood will prompt a person to make corresponding reactions, which will gradually precipitate into the subconscious, thus playing an important role in the future.
About great changes and psychological trauma.
The first thing that comes to mind is the understanding of "death". When a person encounters death for the first time, whether he encounters a real death event or understands the meaning of the word "death", it is a shock to his inner world. Therefore, it is best not to really understand the physiological and philosophical significance of death before forming a mature and stable personality at a young age. If a young child asks about death, he must make up a fairy tale.
Then there is the loss of what you love, and the loss of spiritual pillars such as values, ideals and hopes. In fact, this is another aspect of "death" and "non-existence".
If you are interested in parent-child relationship, family environment and character formation, I recommend two books:
Why do family members hurt people? Wu Zhihong, Beijing United Press.
Why does my family affect my life? Henry Marcy, Nathan Seinberg, World Book Publishing Company.
The previous book is the work of domestic first-line psychological counselors, which explains many psychological mechanisms and the reasons for these phenomena with many examples.
The latter book is based on a 30-year follow-up study, which tracks the growth experiences of more than 70 people from 6 weeks old to 30 years old.
Finally, back to MBTI, why are some types of people prone to depression, some types of people are more sensitive, and some types of people seem too enthusiastic and selfless ... If you do a 30-year follow-up study, you will probably find out what kind of people will grow up in a good family environment.
Of course, just like traumatic events, there will be healing events. In addition, the mind also has the ability of self-repair and self-destruction. Therefore, although the experience at the beginning of life has a great influence, the personality will still change with the long years and experiences.