In Old French, genitive structures both mirrored and differed from those found in Modern French. Prepositional genitives were found (i.e., la nièce au duc, la nièce du duc both ‘the duke’s niece’), but there were also structures without prepositions, the juxtaposition genitive, JG (cf. Arteaga D. On Old French genitive constructions. In: Amastae J, Goodall G, Montalbetti M, Phinney M (eds) Contemporary research in Romance linguistics. J. Benjamins, Amsterdam, pp 79–90, 1995; Arteaga D, Herschensohn J. A phase-based analysis of old French genitive constructions. In Colina S, Olarrea A, Carvalho AM (eds) Romance Linguistics 2009: selected papers from the 39th annual conference of the Linguistic symposium on the romance languages. J. Benjamins, Amsterdam/Philadelphia, pp 285–300, 2010; Delfitto and Paradisi 2009) type la nièce duc or la/le duc nièce.). In an analysis focusing on the evolution of the genitive, we propose that the JG in Old French has directly inherited the same structure in Latin, although Latin had no definite article. In later OF, when case endings ceased to be pronounced, case had to be checked by a preposition. At that point, children no longer had the morphological cues (Lightfoot D. The development of language: acquisition, change, and evolution. Blackwell, Oxford, 1999) to assign a genitive meaning to the possessor, the JG was lost. The reason for the narrowing of the à genitives can be explained by the fact that dative à has always been limited to persons (Herslund M. Problèmes de syntaxe de l’ancien français. Compléments datifs et génitifs. Akademisk Forlag, Uppsala, 1980).