Humans are creatures of habit. Functionality becomes ingrained into definite patterns which become harder to modify with age. Practice and training can result in the initial ability to put into use a wide range of different configurations (ie many skills), but usually most individuals opt in the end to specialize and retain functionality in a narrow range as they get older. If you don't use it you lose it. This applies to all functionality in all areas of endeavour.
Entrenched behavioural patterns are physiological. They involve nerve and brain tissue, muscle, ligament, bone and other tissue or organs working in particular configuration in relation to each other. Mental habits too, involve configuration of neurons and synapses that develop within the brain. Nerve strands, muscles, organs, attachments to bone and other elements have to develop in a certain way to produce a certain overall result for the organism. Some of these configurations happen as a result of informal experience and some result from intensive training with skilled instructors.
Entrenched patterns are beneficial in that once a functionality or skill has been acquired, then it is easily kept and maintained. They are disadvantageous in that they retain established dysfunctionality with equal vigour.
Behavioural patterns are established during the long childhood and adolescence periods as bone and tissue matures and becomes consistent. After about age 20 any change will involve considerable dedication and time. By age 60 the cells of the body have become so crystalized that further change is very difficult indeed.
When considering behavioural patterns, the actions of the brain have to be considered as physiological events. During development, nerve strands grow along certain paths as they are needed, providing essential information on stimuli in the environment. The brain is not a CPU fully decked out with circuitry from the moment of birth, but rather creates its own circuitry during upbringing in response to the stimuli and experiences of the growing child. The brain develops its structure according to the behavioural patterns of that child. Connections that are regularly used will be reinforced, those that aren't will wither. During this time lots of potential avenues for development will get blocked off as behavioural selection takes place. An active child may turn down intellectual development by attending mostly to external stimuli. A reticent child might turn down physiological functionality by focusing on developing intellect. Each behavioural pattern will result in different brain, nerve and tissue structure.
If a child grows according to a certain pattern and then in adulthood it is found to be dysfunctional, then the task of changing it is quite considerable. There is a whole physiological structure of brain, nerve and tissue that has to be undone and then restored in a different form. To do so requires considerable time and dedication.
The subconscious refers to behaviour (including thoughts) that has become entrenched into the physiology (including the brain) during development. Usually this behaviour was initially processed consciously some time in the individual's past.
As an example a child learning to swim consciously extends certain behaviours at the encouragement of their coach, such as how to hold the head, when to stroke and how to kick. During the training period their swimming might be awkward as they think of what they are supposed to do and as their physiology develops, but once they reach adolescence and they have practiced a lot then the act of swimming doesn't require much conscious intervention. At that point they can swim subconsciously.
The same applies to the act of walking, talking and any skill that as an adult we take for granted. Much of what we do we had to learn consciously at some earlier, now forgotten, stage in our development, but because of that learning we now are able to carry out these skills more or less subconsciously.
The subconscious is not a region of the brain where thoughts are stored, but a complex configuration of brain, nerve, tissue and bone that becomes entrenched over time and with use and that represents many of the particular qualities of an individual's functional development.
The robust nature of entrenched patterns has led to assumptions that some functionalities are inborn rather than environmental. There is no connection between functionality and any kind of inborn or genetic inheritance. Highly functional or dysfunctional people can spring up anywhere and at any time.