It's interesting to read articles like this, describing the culture you take for granted to outsiders. I devoured Ture Sventon, Kalle Blomkvist and Agaton Sax a

It's interesting to read articles like this, describing the culture you take for granted to outsiders. I devoured Ture Sventon, Kalle Blomkvist and Agaton Sax as a child, but I had never thought of them in the broader context of Scandinavian Noir. You can sort-of see the connection, but it's a bit tenuous: all of these take place in child-appropriate idealized world, they have nothing of the social realism/commentary of Sjöwall/Wahlöö and the later Scandinavian noirs. A closer comparison might be The Adventures of Tintin (obviously not Swedish, but hugely popular in Sweden), which had some of that "social commentary + detective stories", but even that is a bit weak. I think it is fair to say that the genre was essentially invented by Sjöwall/Wahlöö. There isn't much precedence, and you can see strong traces of them in all of their successors. If you're going to trace their inspirations, I would suggest that you shouldn't seek it so much in detective fiction, but rather in things like naturalism and other lefty/socialist fiction movements. Emile Zola is a better place to look than Dashiell Hammett.