Where does “sen paremmin” come from?

sen paremmin (Finnish) comes from Finnish se, from Proto-Finnic se, from Proto-Uralic śe — it.

Ancestry of “sen paremmin”, step by step

sen paremmin traces back through two separate lines of ancestry.

via Finnish se

StepLanguageWordMeaning
1Finnishseit; that; he, she
2Proto-Finnicseit
3Proto-Uralicśeit

via Finnish paremmin

StepLanguageWordMeaning
1FinnishparemminInstructive plural form of parempi; better
Every word from Proto-Uralic śe →Every word from Proto-Finnic se →Every word from Finnish se →