I believe most narcissists experience some sort of abuse or trauma event as young children that prevents them from growing emotionally; they grow into adults with the emotional needs and responses of a child. There may be some defect in the brain that does not allow the structures of the brain to develop that would allow adult emotional regulation, but either way, this is not the fault of the narcissist to have been born with a deformity or abused or traumatized in some way that left them emotionally crippled for life. That doesn’t give them permission to treat anyone badly, it is simply a recognition of fact.
So, to answer your question: in my opinion, narcissists are narcissistic from birth. In the same way that a two year old child is selfish, unaware, unempathetic, demanding and emotionally volatile, the adult narcissist is also all of those things because he or she is simply not able to handle their emotions like a grown-up and is incapable of developing compassion or recognition of others as human beings with needs and feelings of their own.
I am trying to be careful NOT to condone or excuse the adult narcissist’s abusive behavior; no one should tolerate mistreatment from another person in a relationship between adults. If you are raising a child, it is sometimes the case that the child will get frustrated and angry with the adult caregiver and lash out physically or emotionally, have temper tantrums when tired, hungry, or told ‘no,’ and that is an expected part of their development, just as learning how to deal appropriately with meltdowns and tantrums is part of the adult's journey as a parent. However, it is not acceptable, normal, or desirable to have to parent another adult.
Once you recognize that a relationship is toxic in this way , it is best to end it. Name-calling the toxic party is not helpful to them or to you. They are what they are, they were likely born that way or have been that way from a young age, and you can’t fix, change, or help them. You are only in charge of your own change and healing.
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