When making a "Self-Join Many-to-Many junction table, four ID's are created (see video at 4:40 thru 5:06). The junction table "ID", the "PersonID", the "RelativeID" and the "RelativeTypeID". The junction table "ID" identifies elements within the junction table. The "PersonID" identifies elements within the Person table. The "RelativeTypeID" identifies elements within the RelativeType table. The "RelativeID" does not identify elements in a separate table; it identifies elements in the Person table. Therefore, both the "PersonID" and the "RelativeID" identifies elements in the Person table. I can understand How the "PersonID" is related to the Person table - there is a common name, but I do not understand how the "RelativeID" is related to the Person table - the names are not common. What magical SQL dust causes the "RelativeID" to identify elements only in the Person table and not the RelativeType table???