If memory serves, Wisconsin also didn’t care until there was copper discovered in the UP, and then they tried to lay claim - but by that point the Yoopers had been Michiganders for like 70ish years, and Wisconsin’s claim was immediately shot down.
Human beings are sexually dimorphic, but most of the advantages or disadvantages are negligible or can be overcome with training, so it makes little difference. It makes even less difference in middle and high school aged children, since everyone is at (somewhat) different points developmentally anyway.
Its less about the war and more about journalism and the limits of the human capacity for violence over time. IMO excellent film, amazing performance from Kirsten Dunst