The extreme strength of jealousy in patriarchal societies is due to the fear of falsification of descent. This may be seen in the fact that a man who is tired of his wife and passionately devoted to his mistress will nevertheless be more jealous where his wife is concerned than when he finds a rival to the affections of his mistress. A legitimate child is a continuation of a man's ego, and his affection for the child is a form of egoism.
Source: Bertrand Russell :Marriage and Morals, 1929
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