about 2 months ago - PDX-Trinexx - Direct link
Game rules with dramatic effects on gameplay and difficulty (such as gay marriage, or no end date) result in achievements not matching up with the challenge they're intended to provide.

As it's not currently feasible for us to balance achievement difficulty against rules that cause the game to play wildly differently from the base experience, we opted to simply make them unavailable if these rules are enabled at this time.
about 2 months ago - PDX-Trinexx - Direct link
Originally posted by UndocumentedFenian:
Originally posted by PDX-Trinexx: Game rules with dramatic effects on gameplay and difficulty (such as gay marriage, or no end date) result in achievements not matching up with the challenge they're intended to provide.

As it's not currently feasible for us to balance achievement difficulty against rules that cause the game to play wildly differently from the base experience, we opted to simply make them unavailable if these rules are enabled at this time.

Cheers your answer is really helpful. I'm just curious then achievements are allowed when you invert gender laws in the settings, is that because it still shows bias to one gender over another even though female dominated cultures and religions weren't really historically accurate?

More or less, yes. The core gameplay remains unaffected beyond inverting genders, so there's no dramatic shift in how you play the game.