Essentially what I said above. Did the huge violence of the war lead to a period of decreased violent crime/domestic violence as some sort of cultural catharsis? Or did PTSD/exposure to violence lead to an uptick? Or was there no effect at all?
no. Pinker's book on violence has some good graphs on this. Essentially there is a long term negative trend in violence in the 19th and 20th century that the world wars don't really have an impact on. Literally the year after the war ended there is a bump in homicides over expectations (everyone getting back) but in the long view there just isn't a connection here worth noting. Short and long term trends from before the wars had much more of an impact on trends
here are a couple of graphs i pulled from the internet
http://marginalrevolution.com/wp-content/uploads/2011/05/Violence-Stylized-2.png
http://thepublicintellectual.org/wp-content/uploads/2011/03/Homicides-1900-2010-2.jpg
http://gunfreezone.net/wordpress/wp-content/uploads/2014/09/murder-1900-to-2011.png
