I know they don't like to talk about it much, but these differences ~ as minor as those of us outside that part of the world might think them to be ~ have been sufficient to create wars many times over the last few centuries.
There are libraries of books written about Danish psycho-social incompatibilities ~ and they paint a frightening picture.
The only wars that could fit this picture I remember are the Prussian-Danish Wars over Schleesvik-Holstein during the unification of Germany, and the Second World War. The border was afterwards fixed according to population majority of each area.