 Due to the similarities in synonyms it was long thought that Persan was the same grape as Étraire de la Dui which is also found in the Savoie wine region.In 1902, L. Rougier, an ampelographer writing for Pierre Viala and Victor Vermorel's catalog of grape varieties, determined that the two were separate varieties with Étraire de la Dui likely being an offspring of Persan.Over a 100 years later, DNA testing conducted by Swiss geneticist José Vouillamoz "strongly suggested" that there was, indeed, a parent-offspring link between Persan and Étraire de la Dui but in what direction (i.e.