CPTSD (complex, as in multiple) produces psychosomatic responses, anywhere from coloring your world view to rewiring your brain, to causing parts of your brain to never develop. So, very much the past creates who you are, as surely as removing an arm when you are a child.

Like, if you do not get your mother's love as a child, you will be forever looking for love (to fill a hole in your soul) AND you never quite know what love is.

If your mother was borderline, you grew up never knowing normalcy, safety or security. As an adult you will be hyper-vigilant, never able to just relax.

So, as an adult you can heal much of the traumas, but you will never be like you were if they never happened. And healing isn't just about talking it out, it usually needs "working it out of your body".