What is the importance of childhood & adolescence, according to Buddhism?
What I mean by that: Much of our psychology is related to child and adolescence. Phobias, for instance, can develop from childhood. You're stung by a bee as a baby and the trauamatic experience creates an automatic response for terror, which lives on up until adulthood.
As I understand notself, it doesn't mean that there is no personality at all, but that there is no enduring personality, such as a soul; that is, there are particular arrangements of mental-physical factors, but those arrangements are transient. So, we can have some reasonable expectations of how we all might act. Based on how he is right now, I don't reasonably expect Retrofuturist to murder or rape anybody.
...And much of this make-up comes from childhood and adolescence. Although the personality can change at any type, practically-speaking, most of the changes in the personality, the brain, etc., occur in childhood & adolescence. Up until about the age of 25, I'd say, what once had the consistency of water (infancy & childhood) and then glue (adolescence) has now become cement. So, changing one's habits at an old age, or learning new things at an old age, is like trying to lay a foundation with cement that's already dry or trying to grow fresh crops from an aging plant instead of a seed. Like the saying goes, you can't teach an old dog new tricks. It is possible, of course, but much more difficult.
This is one of the reasons why I think many people are interested in past lives: If childhood and adolescence is so important, how much more so past lives must be! My particular dispositions today might be the result of being a murderer or rapist in a past life, or a demon, or a fallen deva, or whatever else. Apart from the vanity that drives such speculation, it is also possible to really want to know in order to fully understand the present situation. I may have, for instance, done terrible things to the people that I hate in this life, which gives a helpful context to the situation.