Kammala jumla mai zuwa: An haife shi a Viroflay, Yvelines, shi ɗan'uwan masana kimiyya ne Axel Kahn da Olivier Kahn, kuma ɗan mahaifin Bayahude da mahaifiyar Katolika. Bayan ya sami digiri a tarihi, ya soma aiki a ofishin rarraba wasiku, sa'an nan kuma a wurin buga littattafai. Ba da daɗewa ba ya koma aikin jarida kuma an aika shi don rufe
yaƙi a Algeria, gudanar da bincike na aikin jarida wanda ya zama sananne a matsayin "Ben Barka affair". Daga nan Kahn ya yi aiki a matsayin mai ba da rahoto ga "Paris-Press", "L'Express" da Turai 1. Daga baya ya koma "Le Monde" a matsayin wakilin musamman na Arewacin Afirka. A shekara ta 1977, ya zama editan tarin "Nouvelles Littéraires" kuma a shekarar 1983, an nada shi editan "Matin de Paris". A cikin 1984, ya kirkiro "L'Événement du Jeudi" sannan a cikin 1997, tare da Maurice Szafran, ya fara mujallar mako-mako, "Marianne", inda ya kasance babban edita har zuwa 2007. Sau da yawa yana rubutu a ƙarƙashin sunan François Darras ko Serge Maury.