Separation of Sex from Procreation preceded the Separation of Sex from Gender
As societies industrialized and created social welfare programs, having many children went from being a financial asset to a liability. This realization combined with the invention of adequate birth control, and concerns about over population, led to a decline in pro-natalism. This decline a allowed a divorce of sex from procreation. People who no longer based their gender and sexual identities solely on their role in procreation became freer to express them outside of the socially prescribed norms.
