You asked me where in the Bible it says that original sin is transmitted through the biological father. Is that in the Bible - or for that matter the Immaculate Conception etc?
But actually, Catholic doctrine holds that original sin is transmitted through the father. This is not an area of disagreement between Protestant and Catholic. I was a little surprised that you were asking that.
In the Roman Catholic tradition, Original Sin is, as mentioned above, passed down from father to child; the transmission occurs through the sexual act. Since Christ's Father is God Himself, there was no Original Sin to be passed down. Conceived by the Holy Spirit through Mary's willing cooperation at the Annunciation, Christ was not subject to Adam's sin or to its effects.
Mary, however, was preserved from Original Sin in a different way from Christ. While Christ is the Son of God, Mary's father, Saint Joachim, was a man, and as all men descended from Adam, he was subject to Original Sin. Under normal circumstances, Joachim would have passed that sin on to Mary through her conception in the womb of Saint Anne.
God, however, had other plans. Saint Mary, in the words of Pope Pius IX, was preserved from Original Sin "in the first instance of her conception, by a singular grace and privilege granted by Almighty God." (See the Apostolic Constitution Ineffabilis Deus, in which Pius IX infallibly proclaims the doctrine of Mary's Immaculate Conception.) That "singular grace and privilege" was granted to Mary because of God's foreknowledge that she would, at the Annunciation, consent to be the mother of His Son. Mary had free will; she could have said no, but God knew that she would not. And so, "in view of the merits of Jesus Christ, the Savior of the human race," God preserved Mary from the stain of Original Sin that had been mankind's condition since the Fall of Adam and Eve.
So what I said in post 69 is affirmed by Catholic doctrine:
Somehow Mary was able to be without the taint of original sin with a biological father but Jesus was not if we believe Catholic theology.
This, to me, is rather ludicrous.
You will have to provide a citation for your dogmatic assertion that the Catholic Church teaches that original sin is passed strictly in the paternal line. “Natural propagation” is what the Church defined at the Council of Trent.