What is my likelihood of having twins naturally?

A little history. My fiance's sisters are twins, and so are their uncles. I had my palm read randomly and what told I was going to have a set of twin girls. I told my mother, who then informed me that her mother had a set of twins (I never knew because one had become estranged from the family long before the grandkids were born.) I've heard that twins are ped on the maternal side, and skip a generation, though I have no idea if there is any truth to that statement. Does anyone know my actual percentage of having twins??