Personally, I would like to see more of a 50-50 balance of male to female thralls appearing on all of the maps.
From the days of Early Access, I never understood why the majority of thralls found were males.
While there are some mods that will increase the chances for females to appear, I would prefer a more balanced approach in the base game. At the very least, there should be an admin control that tweaks the percentages. More options is always better.
