Augustine used Romans 5 to hypothesize that sin comes to humanity through the father, thus the need for Christ to be born of a virgin. How does this hypothesis impact humanity in our understanding of the necessity of Christ's blood as the propitiation

Augustine used Romans 5 to hypothesize that sin comes to humanity through the father, thus the need for Christ to be born of a virgin. How does this hypothesis impact humanity in our understanding of the necessity of Christ's blood as the propitiation (c.f. Romans 3:21-26; Hebrews 2:17) for our sins?