Complex sentence: George du Maurier was the father of Gerald du Maurier and so grandfather of the prominent writer Daphne du Maurier, and also grandfather of the Llewelyn-Davies boys who inspired "Peter Pan".
Split into simpler sentences: George du Maurier was the father of Gerald du Maurier and grandfather of the prominent writer Daphne du Maurier. He was also the grandfather of the Llewelyn-Davies boys who inspired "Peter Pan".