The core Germanics (Austria, Liechtenstein, Switzerland, Prussia, and Germany) are all siblings.
Belgium, Netherlands, and Luxembourg are half-siblings to the core Germanics.
The Nordics (bar Finland) are their cousins.
(This is my attempt at trying to make Hetalia families make sense. The core Germanics are tied together by a common language and similar culture--though dialects vary. The Low Countries are Germanic countries, but also had history of Celtic tribes being there. The Nordics' languages are Germanic, except for Finnish. They also have a history of Germanic tribes migrating there.)
