I'll try...

To me it's a traumatic event or events that occurred during childhood that affected our personality in a negative way. Basically we were placed in situations where we hadn't yet developed functional coping skills and dealt with problems the best we could, and those skills were dysfunctional and affect our personality to this day. It's what we know, and a personality is hard to change.

try and detach and feel nothing. also, a dysfunctional way of coping because i can't figure out a functional way. I suspect this is partly because self image and lack of a consistent self.

actual mental illness because it a thought process, way of acting out that affects our life. Most people with bpd have secondary issues such as anxiety, major depression, bi polar, or ptsd or some combination.

see above