The 'origin' of this custom/tradition is not known. = The 'origins' of this custom/tradition are not known. [=no one knows how this custom/tradition started]
He comes from 'humble origins'. [=he comes from a family that did not have high social status or much money]
The English word “rendezvous” is French 'in origin'. [=the English word comes from French]
(..) In other words, we could be inside an event horizon. Perhaps we are actually living inside a black hole. Narrator: Every black hole might be the origin Of an entirely separate universe. If that's true, There could be billions of universes out there... (..)2010 TvShow: How the Universe Works Title: Black Holes Season: 1 Episode 2