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]
(..) I'll be administering your test. You'll be offered a series of choices to test your aptitude for each faction until you get one result. I wouldn't sweat it. % get the faction of their origin, and from the looks of you... What is it? Bottoms up. Choose. Now. Before it's too late. (..)2014 Divergent