He married
Maud, an illegitimate daughter of King
Henry I of England before 1113. Conan and Maud had three children that are known: •
Hoel (1116–1156) – disinherited from the ducal crown; Count of Nantes; •
Bertha (1114 – after 1155) – married
Alan of Penthièvre; upon Alan's death in 1146, she returned to Brittany; • Constance (1120–1148) – married Sir Geoffroy II, Sire de Mayenne, son of Juhel II, Seigneur de Mayenne. ==Succession==