On a related note... Kernberg thinks that explanation of BPD bottoms out at an innate, pathologically intense, agressive drive.

Kohut disagrees. He thinks that agression can be explained as a response to frustration of needs.

Linehan explains BPD with a diathesis - stress model where BPD arises from a combination of innate dispositions to intense emotional responses with slow return to emotional baseline and an invalidating environment where parents aren't adequately nurturing / validating.

Schore explains the diathesis - stress model in a little more detail. Needs can be frustrated because the infants needs exceed the (m)others ability to provide. This could be because of facts about the infant (e.g., sickness so (m)other is unable to soothe effectively) or facts about the (m)other (e.g., finding feeding painful so cringing from baby when it wants to be soothed / fed) or even more likely an unfortunate combination.

There are a lot of explanations out there...

IMHO... Pick one that leads you to feel better about yourself. The truth is likely to be found in some combination but I really do think that some theorists are unnecessarily pathologising. Most often because... They feel powerless / frustrated in their ability to help hence engage in 'blaming the victim'.