Where does “kiss your sister” come from?

kiss your sister (English) comes from English KISS, from Middle English kissen, from Old English cyssan, from Proto-West Germanic *kussijan, from Proto-Germanic kussijaną, from Proto-Germanic -janą, from Proto-Indo-European -yéti, from Proto-Indo-European yé- — he, she.

Ancestry of “kiss your sister”, step by step

kiss your sister traces back through 3 separate lines of ancestry.

via English KISS

StepLanguageWordMeaning
1EnglishKISSAcronym of keep it simple, stupid; The KISS...
2Middle Englishkissento kiss
3Old Englishcyssanto kiss
4Proto-West Germanic*kussijanto kiss
5Proto-Germanickussijanąto kiss
6Proto-Germanic-janąDerives denominatives from nouns and factitives...
7Proto-Indo-European-yétiCreates intransitive, often deponent,...
8Proto-Indo-Europeanyé-
9Chichewaiyehe, she

via English your

StepLanguageWordMeaning
1EnglishyourBelonging to you; of you; related to you; A...
2Middle EnglishyourAlternative form of youre
3Old Englishēoweryour plural
4Proto-West Germaniciuwaryour, yours, of you
5Proto-Germanicizwerazyour; 2nd person plural possessive
6Proto-Germanicjūzyou
7Proto-Indo-Europeanyū́you
8Proto-Indo-Europeantúh₂you, thou

via English sister

StepLanguageWordMeaning
1EnglishsisterA daughter of the same parents as another person;...
2Middle EnglishsusterA sister or step-sister; a female sibling
3Old Englishsweostorsister
4Proto-West Germanic*swestersister
Every word from Chichewa iye