Though your comment is downvoted, it is broad terms quite correct. There is strong evidence of a genetic component to BPD. It is a personality disorder and the

Though your comment is downvoted, it is broad terms quite correct. There is strong evidence of a genetic component to BPD. It is a personality disorder and therefore a result of (abusive) training in childhood. And it is possible to learn to improve one's emotional instability. I do have the sense that you're simplifying the issue in away that disguises the more complex reality of BPD. I do not recall the genetic factors pertaining to emotion. A failure to regulation one's emotions is partly connected to a general impulsivity which arises in a traumatic environment where you are always on high-alert. NB. It's always interesting what gets down-voted on hacker news. The police will chastise commentators who are too emotive in their phrasing but not the downvotes who most actively prevent open discussion.