Several factors contributed to the discovery of Wnt genes. On the one hand, the development of research tools in mammalian genetics such as mouse strains with high incidence of cancer in 1920-1930s led to discovery of the mouse mammary tumor virus in 1949. This virus in turn was used in 1982 to identify int-1 (Wnt1) in mammals. On the other hand, a discovery of the wingless mutant in 1973 resulted in cloning of the wingless (wg) gene in 1987. A comparative analysis of int-1 and wg led to the realization that these genes are evolutionarily related. This brought about a harmonization of names for a whole family of these genes now known as the Wnt family of genes. This review mainly focuses on what stood at the cradle of research on Wnt genes, and in particular on those elements that were nearly lost in history.