Complex sentence: Descended from the ancient Breton family currently represented by Josselin de Rohan, the 14th Duke, he was the only son of General Louis-Guy-Charles-Guillaume de Rohan by his wife Lady Isabelle Fitzgerald.
Split into simpler sentences: Descended from the ancient Breton family currently represented by Josselin de Rohan, the 14th Duke. He was the only son of General Louis-Guy-Charles-Guillaume de Rohan by his wife Lady Isabelle Fitzgerald.