Léa Chaillou believes that he was born circa 970, the son of Alan de Léon, himself the son of a possible great-granddaughter of Alan I, King of Brittany.
This rise in power threatened Alain Canhiart, the Count of Cornouailles, who was victorious in 1055 and gave the hamlet of Lezugar en Beuzec to the episcopal authority.
[5] Guihomar is said to have had a son named Éhuarn but according to Joëlle Quaghebeur Ehuarn was actually a “Viscount from Cornouaille”, that is to say of a Viscount of Le Faou who married a woman belonging to the House of Léon.
Alan II had three children, Guihomar, Anne/Emma who married Odo I, Viscount of Porhoët and another daughter, name unknown, who married Ehuarn II, Viscount of Châuteaulin.
[7] He was undoubtedly succeeded by his supposed grandson and namesake Guihomar II as Viscount of Léon.