English and French from Old French and Greek "well-born, noble". The French form has an accent: Eugène.
It is also the Anglicized form of the Irish Gaelic Aodh and Eóghan, plus a number of variants. Euan/Ewan/Ewen may also be Anglicized as Eóghan so are here classed as Lesser Synonyms of Eugene.
In old documents in Latin, Eugenius is used for Euan/Ewan/Ewen as well as for Eugene. Care must be taken when searching to allow for Latin case endings.
The short form Gene is now a popular given name, especially in the US.