Sleep Paralysis Hereditary?

A couple of people I know have started to experience sleep paralysis on a pretty regular basis. They know that I know quite a lot about dreaming and sleeping and I have spoken to them about sleep paralysis before so they came to ask me about it and I gave them some general advice, but I noticed something quite interesting; both of them mentioned that other people in their family also experience it quite often (sisters, mother etc).

I have started to suspect that frequent experiences with sleep paralysis may be hereditary but I cannot find any information on it anywhere that confirms/debunks the theory so I want to know:

1) Do you personally experience SP frequently? If so, do any other members of your family also have the same problem?
2) Are there any studies on this that I could read about? I couldn't seem to find any anywhere.