Léon Marchand is no stranger to swimming. On the contrary, his parents led a professional career. His mother, Céline Bonnet, participated in the Barcelona Olympics in 1992 and belonged to the famous Cercle des nageurs de Marseille. His father, Xavier Marchand, won a silver medal in the 200m*4 medley at the World Championships in Perth in 1998 and two medals of the same color at the European Championships in Seville in 1997. His uncle Christophe Marchand was also French champion several times.