Complex sentence: His parents were of German-Jewish ancestry: his father, Franz Mankiewicz, was born in Berlin and emigrated to the U.S. from Hamburg in 1892 with his wife, a dressmaker named Johanna Blumenau, who was from the German-speaking Kurland region.
Split into simpler sentences: His parents were of German-Jewish ancestry: his father, Franz Mankiewicz, was born in Berlin and emigrated to the U.S. from Hamburg in 1892. He was with his wife, a dressmaker named Johanna Blumenau, who was from the German-speaking Kurland region.