INTRODUCTION 'The use of alcoholic beverages is the most destructive agent to the human race. It is destroying us physically, morally and spiritually, both directly and indirectly, by inheritance, handing [...], The Woman's Christian Temperance Union (WCTU) of the United States and Ontario created in the 1880s departments of work dedicated to the study and care of heredity. This article examines the history of these departments and explores how the two organizations made differing use of the concept of heredity to support their particular agendas and methods for social reform. By exploring how heredity functioned as a malleable resource for the WCTU, this comparative case study also serves as an example of the cultural lives of scientific concepts. Keywords. American National Woman's Christian Temperance Union (WCTU); Ontario provincial WCTU; heredity; temperance; popularization of science. Les Woman's Christian Temperance Union (WCTU) des Etats-Unis et de l'Ontario ont cree dans les annees 1880 des services dediees a l'etude et a la prise en charge de l'heredite. Cet article examine l'histoire de ces services et etudie la maniere dont les deux organisations ont fait des usages differents du concept d'heredite afin de soutenir leurs propres programmes et methodes de reforme sociale. En explorant comment la malleabilite de la notion d'heredite a ete utilisee par les WCTU, cette etude de cas comparative entend egalement participer a l'etude de la vie culturelle des concepts scientifiques. Mots-cles. Le Woman's Christian Temperance Union (WCTU) americain; La branche provinciale ontarienne du WCTU; heredite, abstinence; vulgarisation scientifique.