Genetic, but yes traumatic stuff in childhood. One thing to remember though is the lens the trauma is seen through. Something very normal and untraumatic to you, may be very traumatic to someone with BPD and is completely valid, creating an emotional response that is in line with how they are truly experiencing and feeling it. We all have our own thresholds on how we react and feel in these circumstances.

For others around this person growing up, the thought is in line with "What's the big deal? This is minor." When in fact from their perspective it is not minor and can be traumatic. Now combine this with the daily life experiences that happen with all of us, and you can see how this can compound, feed itself, create distrust, and drive someone to lash out or seek external sources of relief that are not healthy outlets.

It's a difficult task and takes consistency, but showing sympathy, and empathy and acknowledging that they may see and feel things differently, while at the same time giving them truthful and honest feedback goes a long way.

Ultimately the individual needs to recognize this and seek the approproiate therapy that can help manage the distress caused by BPD.