The authors agree that this surname derives from the proper name given to twin children. E. De Felice notes that it arose from the name Gemello, attributed to children born as twins, and that its transformation into a surname is documented mainly in Lombardy, Calabria and Sicily.

E. Rossoni specifies that the forms Gemelli, Gemello and Gimelli derive from the Latin name Gemellus or Gimellus, of which there is an epigraphic testimony of the 3rd century in Ravenna: T(itus) F(lavius) Gimellus, mil(es) cl(assis) pr(aetoriae) Mis(enensis). Rossoni details that Gemelli presents specific zones in the Milan and Pavia areas, in the province of Genoa, in Emilia-Romagna, in Calabria, in the Naples area and in the Palermo area. The form Gemello is very scarce and appears in small zones of Asti and Lecce. Gimelli, for its part, is concentrated in Milan, in Genoa and in Loano, in the Savona area, as well as in the Forlì area and in Rome.