But it is objectively impossible to find out how exactly were you born. And it seems that you have experienced enough emotional abuse and neglect that it would confound with any other particular trauma and it would still be impossible to say why exactly you have turned out the way you are - because you were born this way or because you had to endure the emotional neglect or because there was still something else. It's just impossible to disentangle it at this point.

The only real thing at this point are your memories (the things you really remember), your thoughts and feelings right now. These are the only things you can realistically work with right now. Also, it wouldn't matter if by some divine means you would find out that you were not born this way - you still have those memories, thoughts and feelings and you would still have to work with them to make peace with yourself and accept yourself the way you are.

As several people have told you, as long as you have thoughts and urges but you are not acting on them you are not bad. Being a person is a messy experience and everyone has their "good" sides and "bad" sides. This is what being human means. Therapy can help to learn to know yourself and accept yourself more the way you are in order to live more fully as the person you are. Therapy cannot help you to become a different person. The healing lies in learning to accept yourself and managing your different sides, both good and bad, better.

I would also like to repeat that false memories are a real thing. It has been shown repeatedly that it is possible to make people "remember" stuff that never happened to them. Your therapist seems very suggestive and I find it dangerous.