When Borel broke his arm at the age of eight, he preferred to run away and hide rather than go home; he was eventually found shivering from pain. In this type of situation, Borel, who was known as a quiet and taciturn boy who kept to himself, grew up and developed an increasing admiration for the military. He told lies about the heroic deeds of his father during the Indochina War and adored his stepbrother Franck Bichet, who served in the army. He had an affection for weapons and used to shoot sparrows with an air gun.