I can definitely tell you it is a Swedish one. There are other nationalities that do it as well, but I must say that my mother's side of the family was 100% Swedish after living here for 100 years, and they did it at the end of every harvest.Add me to the list. My wife's family has always had chili and oyster stew at Christmas. If either of you or @realbp find out where this tradition originated I'd love to know
From what I can see it appears to be either an Irish-Catholic or Italian tradition but the family isn't either one so idk