My grandmother was a narcissist.  My grandfather was codependent.  Who had two narcissistic children and one codependent one. 

Here is a graphic of my NPD Family Tree, so you can understand how this generational narcissism works:

After you look at this family tree, I bet you'd easily be able to make one of your own that looks eerily similar. 

And that's because this is how narcissism always looks.  It follows a pattern.  The only time it deviates is because the narc wants it look like it is.  Like, doing something super nice for you on your birthday when she normally doesn't do anything.  There is always an agenda for everything they do.

If you're just beginning your journey on this narcissistic roller coaster (meaning you just figured out your mom's a narc) or you've been on it for awhile, make your own NPD Family Tree.  It will help you to see who's who and who to avoid and who to seek out.  If you don't know if they have NPD or or not, put a question mark under their name so you can come back to them later after investigating.  Learn everything you can about narcissism and how narcs work, so you an apply what you know to your family so you can find the patterns.  All narc families have patterns, you just have to find them. 

And once you find them, you'll be better off, so you can stop trusting the wrong people.