Wow - this is scary and very complex family dynamics. I am 41, younger brother is 39. We we never particularly close, but as I can see looking back at my past, my NM kind of kept us separate - so she could manipulate us better. Sort of a divide and conquer tactic. She never wanted us to be close - she's never say take care of you sister or brother or you dont do this/that to your sister/brother. Too self absorbed to care about how others treated us, I suspect. Its become routine that friends and bosses treated me badly, and it went unrecognized from her and without any compassion or empathy when I brought it up. I can see now that my blind spot was formed here because I always had trouble getting any support when I'd been wronged.
Anyway, in the last three months or so, my brother admitted to me that he thinks NM is BPD. He found this out while in counseling from his first divorce. His first wife, who my NM despised turned out to be quite alike. I was kind of pissed that he never mentioned it before, because I'd been struggling with issues and it would have helped. He once said he thought she was "crazy" , but I did not take that careless wording as an assessment. Had he said, I've been in therapy, my T thinks she is BPD, well thats would have meant something. He also admitted that she is quite a LIAR, which I suspected, but I thought it was more emotional dishonesty for manipulation. Now I actually know that she is 100% dishonest, mostly about family finances and other things.
Anyway, we might disagree here a little - I think shes N, he thinks not so much, but we do agree (with the help of both of our therapists) that she has a PD.
For the statistics, he is on his second marriage and I have just ended a one year relationship but have never been married. He is also temporarily apart from his wife and he has three boys - two from the first, one from the second. I'm anxious to see how their mothers Nism will affect them as they grow up. I went through a whole period of discovery with NPD and its been quite a journey, and now I see my blind spot, its both brought me a relationship and destroyed it at the same time.