Griete was the daughter of Geert van Tybencamp but her mother is unknown. The date and place of her birth have not been found.
Her husband was Roelof van Ittersum. They were married, but the date and place have not been found. Their eight known children were Jan (?-c1464), Wolf (?-<1420), Geert (?-?), Jacob (?-?), Zwane (?-?), Lutgert (?-?), Griete (?-?) and Lyse (?-?).