Why does low self esteem affect me now?
We might reasonably assume that what happened in the past should stay in the past because rationally we are not experiencing it now. However our subconscious contains everyone we’ve ever been, the sum total of our experiences. Plus, we’re talking about belief here, not reasoning. Specifically the belief of the child who created our self concept. This is why you might know that you are fine cognitively but often feel the opposite with no rational basis.
Imagine our self concept is created much like building a house. The foundations of the house are our beliefs about ourselves from our formative years. So the house that is constructed upon these foundations will be affected by them. If the foundation have a crack running through them, then the house will have that same crack.
Worst still, because this is a ‘belief’ it is relatively impervious to logic and pervades our view of the world and our place within it. We use the belief to apply confirmation bias to our experiences. For example, if I believe at my core I’m a failure, I will largely ignore evidence that implies otherwise. I might get 99 out of a hundred questions right in a quiz but obsess about the one that I got wrong and use it as evidence of my lack of value. I might still feel a failure. We also might desperately crave what we lacked in childhood in our adult life. Approval or praise for example, but then when offered it, reject it because it does not fit with our established beliefs about ourselves. Essentially a no-win scenario. These examples show the types of contradictions within us because of the primal belief we hold about ourselves.
It’s a lens we are looking through, tinted with self doubt. This sensitivity will probably make us more uncomfortable in circumtances that emotionally mimic our childhood experiences. For example, if one of my parents abandons me as a child, I might reasonably fear abandonment in my relationships generally, fearful or opening that emotional wound again. The are once again infinite possible reasons for creating this feeling but they mainly happen in childhood.