Where does “thắng về nội, thối về ngoại” come from?

thắng về nội, thối về ngoại (Vietnamese) comes from Vietnamese vẽ, from French vé, from Occitan vei, from Occitan veire, from Latin vitrum, from Proto-Italic wedrom, from Proto-Indo-European wedro-, from Proto-Indo-European wed- — to wither; fade; to move, go ahead; to be strong;...

thắng về nội, thối về ngoại (Vietnamese): The paternal family (father's side) is credited with good things while the maternal family (mother's side) is blamed for bad things

Definitions

  1. The paternal family (father's side) is credited with good things while the maternal family (mother's side) is blamed for bad things

Ancestry of “thắng về nội, thối về ngoại”, step by step

thắng về nội, thối về ngoại traces back through 3 separate lines of ancestry.

via Vietnamese vẽ

StepLanguageWordMeaning
1Vietnamesevẽto draw; to paint; to contrive
2FrenchThe name of the Latin-script letter V; calf; API!
3Occitanvei
4Occitanveireto see
5Latinvitrumglass; a woad; a plant used for dying blue; woad;...
6Proto-Italicwedromglass
7Proto-Indo-Europeanwedro-water-like
8Proto-Indo-Europeanwed-water
9Proto-Indo-Europeanwey-to wither; fade; to move, go ahead; to be strong;...

via Vietnamese thối

StepLanguageWordMeaning
1Vietnamesethốirotten; fetid, putrid, stinking, foul-smelling;...
2Proto-Chamic*ʔadhɛ̃yforehead
3Proto-Malayo-Polynesiandaqihforehead
4Proto-AustronesiandaqiSforehead

via Vietnamese thẳng

StepLanguageWordMeaning
1Vietnamesethẳngstraight
2Chinese
3Proto-Sino-Tibetanr-la(w)ŋsteam; hot
Every word from Proto-Indo-European wey-