Complex sentence: Her paternal grandparents were King James I of Scotland and Jane Beaufort, and her maternal grandparents were Arnold, Duke of Guelders and Catherine of Cleves, daughter of Adolph IV, Duke of Cleves and Marie of Burgundy.
Split into simpler sentences: Her paternal grandparents were King James I of Scotland and Jane Beaufort. Her maternal grandparents were Arnold, Duke of Guelders and Catherine of Cleves, daughter of Adolph IV, Duke of Cleves and Marie of Burgundy.