Question
Is BPD preventable?
Short answer: yes and no, no more so than becoming an 'addict' is preventable.
Longer short answer: yes [by having an excellent environment that doesn't have environmental factors] and no [genetics]; however, it can be treated and put into remission provided that it is a pure conventional type BPD that exhibits the more dangerous and recognizable symptoms & the pwBPD [person with BPD] wants to be treated.
My personal opinion, based on what I know, and have observed, I would side with Aralia and say it is not preventable.