Question: Who is Princess Isabelle Of Orléans (1900–1983)'s paternal grandfather?
Sentence (from "Prince Jean, Duke of Guise"): (Jean Pierre Clément Marie; 4 September 1874 – 25 August 1940), was the third son and youngest child of Prince Robert, Duke of Chartres (1840–1910), grandson of Prince Ferdinand Philippe and great-grandson of Louis Philippe I, King of the French.
Relevant evidence: Yes