What Is a Foliade?

A foliade is an identical or similar mental disorder affecting two or more individuals, usually members of a close family. The most famous examples in popular culture of what has been called falliade before was the report of these two teachers who were visiting versailles and they felt they had travelled back in time just for a brief moment. Do we have any dates associated with these, or these are just thi lore? Well, we know they were before 19 26, right? Cause that's when e is published. That's where we'd have to start.