what is the genesis of mental illness?

[zenmaster]

Your genetic phenotype (how genes express themselves into certain characteristics) is somewhat determined by your environment, thus genetics + environment determines some aspects of the etiology of mental illness but is not always THE cause of illness. It depends on the type of mental illness, not true for all illnesses.

Could you explain a mental illness to me that is not caused by either the environment someone is exposed to or their genetics?

Free will - people can become confused just as anything may fall into disrepair. The body simply follows the pattern of confusion. Neurosis and if sufficiently disintegrating, psychosis. Genetics and environment were always secondary, as far as cause. How much of and how balanced a "you" is possible to bring here? That's your ultimate determination, limited by desire and will.