Poles often think Finns are depressed alcoholics
There may be some truth to that. The rest of Scandinavia also thinks the Finns are weird, who are not Scandinavians but Finno-Ugrics. I have some insight into this because I have been doing research on Hungarians, who are Finno-Ugric and related to Finns, and are also a depressed bunch.
I think it may have something to do with Celiac Disease, which is prevalent in Finland. They can't digest grains well, and this wreaks havoc on multi-systems in the body, including neurologically.
"Celiac disease is common in European countries, particularly in Ireland, Italy, Sweden, and Austria. In Northern Ireland, for example, one in every 300 people has celiac disease. In Finland, the prevalence may be as high as one in every 100 persons."
So maybe the Poles are onto something there.
*edit: I don't mean to offend Finns in the slightest. I am also part Hungarian and a Celiac, so I view them as related.