They didn't grow up in the gmo soy age as children and got a lot less vaccinations. While the average testosterone levels have dropped by 50% in the male population since 2000, the 1970-1990 men are less likely to eat a lot of the imitation meats and soy products that turns them gay like the younger male population.

They are still young enough to shoot a gun and fight back. Also most grew up in an age when you wouldn't even get in trouble for having a gun at school, because the media hadn't turned full tilt on its people yet.