(I already covered this topic in a video, see below; this article is for documentative purposes, so the article version thereof)
People are the product of their environment- that is correct in full, in general; a stable environment produces stable people. The opposite, just that: the opposite- and so on. “The apple doesn’t fall from the tree” is a (global) saying referring to this topic exactly. Below I explain in detail.
The factors that decide someone’s personality are length of life & gender (mainly); the strongest growth takes place (these are estimates, keep that in mind) between the age of 0 (so birth) & 12, and it gradually decreases from there. Roughly estimated, 65% of growth is in the range of 0-12, 12-18 accounts for 25% and the remaining 10% between 18-25. After that, your personality is (more or less) “set in stone”, & will require a lot of effort to alter, adjust or modify in any way/manner. Gender comes into play based on the sex of the child in question; boys will take after the male figure(s) they were exposed to the most in relation to the aforementioned ages, and girls after the female figure(s) in the same way.
The practical logic behind this theory is that, based on the composition of man, your astral body (so spirit) grows alongside its physical counterpart; a physical body that grows up healthy & strong because it grew up in a constructive environment will be just that- solid & stable. An astral body, ditto. I don’t need to point out what kind of person a negative environment will produce…and that’s about it. Again, see below video(s):