Responses
Of course environment can be one of the reasons. Trauma, neglect etc.
But pychos' ( it seems like he wasnt even normal when he was little so probably congenital) brain doesnt function normally. Particularly related to the underdevelopment of the parts of the brain responsible for emotional regulation and impulse control.
So they dont always need to have some trauma to go crazy.
so the twin is fucking insane, bro I don't like born phycos cause why tf u turn out like that when u have a loving family and a nice environment? would've made sense if they had abusive parents and had to be dependent on eachother. also his brother being obviously attracted to him...LIKEEEE