When we are born into a human body we have genetic material, DNA coding. This from a physical father and a physical mother.
That which might at this stage be called id desire and a brain illness such as Factitious disorder is passed down through genetic DNA coding.
A genetic material, DNA coding pass down that results in disorder of the personality most likely will effect each person uniquely. That which happens in a persons life will cause the disorder to manifest differently.
We all have darkness that comes from our genetic material, our DNA. Desires we know are not of the true us which we must overcome.
Desires that haunt us at times, that strive to rise and overcome us.
Such darkness passed through our genetic DNA coding originates from ancestors of our parents perhaps back thousands of years.
Both darkness and abilities pass through to us via genetic coding.