How can I do it? I've tried fertility = X and change_fertility = X; they don't work.
fertile = {
congenital = yes
fertility = 0.4
} # Epigoni Mod - to balance out the infertile trait below
infertile = {
fertility = -1.9
} # Epigoni Mod - used for castration
2 # _CHDEF_BASE_NR_OF_CHILDREN_PER_COUPLE_ ( The number of children allowed per couple )
60 # _CHDEF_ADDITIONAL_CHILD_PROMINENCE_THRESHOLD_1_ ( An additional child will be allowed at this prominence )
120 # _CHDEF_ADDITIONAL_CHILD_PROMINENCE_THRESHOLD_2_ ( Yet an additional child will be allowed at this prominence )
2 # _CHDEF_ADDITIONAL_CHILDREN_FOR_KING_ ( Additional children allowed for kings and queens )
1 # _CHDEF_ADDITIONAL_CHILDREN_FOR_HEIR_ ( Additional children allowed for the heir to the throne in monarchies )
200 # _CHDEF_COURT_SIZE_CHILD_PENALTY_THRESHOLD_ ( When the total number of characters in a country is above this, one less child will be allowed per couple )