I'm not trying to prove you wrong, I'm just questioning this notion that whatever people are born with can't influence on what they become later in life, and that it all can be treated.
So yeah, when you say yourself that a lot of this isn't understood yet and it's all very complex, you can't just claim that people can't be born with anything.
If anything, you're the one trying to simplify things.
Doflamingo is the most complex character we've had in the story. All I'm simply saying is that every individual is born with multiple traits. The environment slowly or drastically draws them out. However, when it comes to Personality/Mental Disorders, they can also be born with that For example, if a child was born into a humble and very caring household, but is very manipulative, unempathetic, and likes the sight of blood from an early age. One could honestly argue that he was born with this trait.
Both of you can't see a difference between character traits and traits one gets because of physiology.
When child is born, he is a clean slate character-wise. He doesn't have opinions, likes, dislikes, political stance, worldview, morality etc.
All of that comes later, from his friends, parents, peers, postman, god, tv, whatever.
If child is born with what is considered disorder, he doesn't get "evil" "asocial" "violent" "unemotional" etc as his traits, life is not The Sims. He just sees world differently, experiences things differently and gets completely different results, which most people without such disorder might consider asocial and wrong. Then such person might get help with ajusting to society, or learn to live society rules, or might not. Even in OP - people can be born with or without COC, but one can be strongest without it, or crying shadow of former self with it. Depends on experiences.
Just like I said in the very beginning, nature is the factor, but most of the personality is formed by outside influence, and same child in two different environments can grow into two completely different people. No such thing as "born evil".