Do you know?/Poznate?

my mother's or father's mother = my grandmother (grandma)
my father's or mother's father = my grandfather (grandpa)
my mother's husband = my father (dad, daddy) or stepfather
my father's wife = my mother (mum, mummy) or my stepmother
my mother's and father's son (I'm a boy and I haven't got a brother) = me
my mother's and father's daughter (I'm a boy) = my sister

Jack is my son, but I'm not his father. Who can say this? Jack's mother (mum, mummy). 

By Romana Ivačič