Tescelin le Roux was born about 1070, son of Tescelin (), a knight of the
lord of Châtillon and Saruc de Grancey. The sketchy available evidence indicates that Tescelin senior was a
miles castri, a dependent knight unrelated to his lord.
Alberic of Trois-Fontaines wrote in the 13th century that Tescelin's mother married Fulk, lord of Aigremont, as well as Tescelin's father. She had a son named Gui by Fulk, Tescelin is described as having a reddish complexion, almost yellow-haired, commonly known as Sorus, or Le Roux.
William of St-Thierry said he was "a man of large possessions, gentle in manners, a great lover of the poor, of devoted piety, and of an extreme zeal for justice ... He never took up arms except in defence of his own lands, or in company with his lord...". In 1085 Tescelin married Aleth de Montbard ( – 31 August 1106). Aleth, also called Alith, Elizabeth or Alix, was daughter of Bernard, lord of Montbar. Their children were Guy, seigneur de Fontaine, Saint
Gerard of Clairvaux, Saint Bernard de Clairvaux (1091–1153), André, Barthélémy, Nivard, Abbé of Hautvilliers and
Blessed Ombeline (1092–1141). A chronicler of Saint Bernard says that his parents were "illustrious by their rank and high descent, but more illustrious by their virtues." ==Career==