Perhaps it's the incarnation of the multiple selves that is the problem, it's quite by accident for the most part but not really I can assure you..
You're a strange one... anyways... suicide CLEARLY is detectable in the brain due to the way the brain chemistry is altered.
I'm going to suggest that there are bacteria out there, that when they overcome someones immune system, forces someone towards suicidal behavior.
The only thing that doesn't make sense is this...
There is also growing evidence that genetics plays a role. For example, according to one study, identical twins share suicidal tendencies 15 per cent of the time, compared with 1 per cent in non-identical twins (Journal of Affective Disorders, doi.org/d23nvw). And a study of adopted people who had committed suicide found that their biological relatives were six times more likely to commit suicide than members of the family that adopted them (American Journal of Medical Genetics, doi.org/fmsncv).
So there is some form of genuine genetic factor at play. Maybe the microbes are passed on from parent to child? But why identical twins at 15% and only 1% in non-identical.
So...