Where does “genner” come from?

genner (Middle French) comes from Middle High German jenner, from Latin iānuārius, from Latin -ārius, from Proto-Italic *-āzios.

Ancestry of “genner”, step by step

Step	Language	Word	Meaning
1	Middle High German	jenner	—
2	Latin	iānuārius	—
3	Latin	-ārius	—
4	Proto-Italic	*-āzios	—

genner — Etymology, Origin & Word History | Etymology Explorer