Where does “sibness” come from?

sibness (English) comes from English SIB, from Middle English sib, from Old English sibb, from Proto-West Germanic sibbju, from Proto-Germanic sibjō, from Proto-Indo-European sebʰ-.

Ancestry of “sibness”, step by step

sibness traces back through two separate lines of ancestry.

via English SIB

StepLanguageWordMeaning
1EnglishSIBHaving kinship or relationship; related by same-bloodedness; kindred
2Middle Englishsibhaving kinship; kinsmen; peace
3Old Englishsibbkinship; peace
4Proto-West Germanicsibbjurelationship, kinship
5Proto-Germanicsibjōrelationship, kinship; friendship
6Proto-Indo-Europeansebʰ-

via English Ness

StepLanguageWordMeaning
1EnglishNessAn Ulster princess and the mother of Conchobar mac Nessa and Findchoem in the Ulster Cycle of Irish mythology. Daughter of Eochaid Sálbuide. Also the mother of Cormac Cond Longas by incest with Conchobar mac Nessa
2Middle Englishnesse
3Old Englishnæsnot, not at all; not; first/third-person singular...
4Proto-Germanicnasjąfoothill; headland; cape
5Proto-Indo-Europeannéh₂snose
Every word from Proto-Indo-European sebʰ-Every word from Proto-Germanic sibjōEvery word from Proto-West Germanic sibbju