From what I’ve gathered, Finnish people spend a lot of time thinking ahead of situations. These situations can be social due to anxiety, going to work tomorrow due to the weather and everything inbetween. And after all this time is spent thinking ahead, the reaction to new and unfamiliar situations is usually not a spontaneous burst of emotion (should it be joy, fear etc.)
But rather an internalised thought of “Oh.. I see” followed by a vocalised afterthought, just so the situation doesn’t feel awkward. Of course, this doesn’t mean we don’t know how to genuinely have fun, but it brings a certain calmness to everyday life, when people close to you are not startled by little things.