Where does “痛くも痒くもない” come from?

痛くも痒くもない (Japanese) comes from Japanese も, from Old Japanese も, from Proto-Japonic mə, from Arabic مَن — who?; who.

痛くも痒くもない (Japanese): Not caring at all, being no skin off one's nose, being of no concern at all

Definitions

  1. Not caring at all, being no skin off one's nose, being of no concern at all

Ancestry of “痛くも痒くもない”, step by step

痛くも痒くもない traces back through two separate lines of ancestry.

via Japanese も

StepLanguageWordMeaning
1JapaneseもUsed to form the conjectural form of verbs,...
2Old Japaneseもnon-unique topic marker: also, even
3Proto-Japonicmənon-unique topic marker: also, even, too, as well
4Arabicمَنwho?; who

via Japanese ない

StepLanguageWordMeaning
1Japaneseないhaving that quality, having that state; very much...
2Old Japaneseない—
Every word from Arabic مَن →Every word from Proto-Japonic mə →Every word from Old Japanese も →