Automatic similarity between primary key and foreign key makes the foreign key adopt the extra fluff of the primary key.

[MartinJohannessen]

(I'm learning so I might be wrong) Concretely, when typing the primary key as a PostgreSQL's "serial" type, meaning it auto iterates, I don't think it would be correct for the foreign key to also be typed "serial" since in that instance it's a normal integer.

[dineug]

In this case, you should disable this option and use it.