A person’s personality refers to the the characteristic behavioral pattern of how the individual thinks, feels, and react. I once sat in for a workshop with a Transactional Analyst (TA) practitioner. In a nutshell, TA talks about how we learn about our world as a child through our interactions with the people around us, especially our parents. TA describes 3 modes of interaction – Adult, Parent, Child. There is more to it which I shall not go into, for those of you interested please google for more information on it. According to her, the personality of a person takes shape around the age of 2 years old. This may have some truths to it as we know that toddlers go through a period known as the “terrible twos”, which is between the age of 1-3 years old. Toddlers enter that stage to test the limits of their world, to form a mental model for which they can use to interact with the world. There is no firm time period for when it begins and when it ends. According to her, she says that we carry that mental schema into adulthood, and when we become stressed we revert to how we react to the situation when we were a toddler. There are also more recent research that says that our personality traits do not become fixed until around the age of 17-18 years old. This is not to say that it does not change anymore, it does change but within statistical limits that would define it as being fairly stable through adulthood.
I think there are merits to both perspective. There is much research that says that we learn how to interact with the world as a child. It is irrefutable that it is the case. However, we make minor tweaks throughout our life to the mental model created as a child, either to add to it or subtract from it. Much like pruning a tree or a shrub, but the tree stays intact the whole time.
Neuro research has also pointed out that when we learn something new, new neuron/s get created in our brains with new pathway getting to the new neuron/s. Overtime, if the pathway keeps getting used, the pathway gets a treatment that makes all signal traveling to it faster (in a manner of speaking); if it becomes disused over time it will get pruned off. It is a well known fact that when we perform an action for the first time, it takes effort to perform. Over time and after many repetition, it becomes effortless (automaticity takes over). Much like our action of eating, drinking, or listening becomes effortless.
In much the same way, when the way we think, feel, and react to situations becomes automatic, it becomes part of our personality. Which is a main reason why personality disorders are so difficult to correct (almost next to impossible). It just takes ALOT of effort on the owner to change it, most of the time more effort than the owner is willing to exert. Thus, when you have a habit that has become like a 2nd nature to you, know that the reason it is so hard to change it is because you have done it for so long, that neuro-pathway has become so strong that it will take a tremendous amount of effort on your part to change. But, change is possible; you have to redecide that YOU WANT TO DO IT. Then commit to exerting conscious effort for a period of time to perform that new habit that you have created to replace the old one.