Among human beings the co-operation of the father is a great biological advantage to the offspring, especially in unsettled times and among turbulent populations, but with the grow of modern civilisation the role of the father is being increasingly taken over by the State, and there is reason to think that a father may cease before long to be biologically advantageous, at any rate in the wage-earning class. If this should occur, we must expect a complete breakdown of traditional morality, since there will no longer be any reason why a mother should wish the paternity of her child to be indubitable.
Source: Bertrand Russell :Marriage and Morals, 1929, Introduction
More info.:https://russell-j.com/beginner/MM-INTRO050.HTM