Does the Catholic church have a dogmatic position on whether original sin is transmitted biologically? Or is it a theological opinion which is optional?
If it is a dogmatic position, what is the doctrinal basis? The answer will need to cite relevant Bible verses + exegesis and/or Patristic writings.
So, like every question that is not obvious or able to be answered in generalities, I think we can only put the boundaries on the things the Church definitively teaches
The Catholic Church teaches that we have first parents (Adam and Eve of Genesis Fame), polygenism (having multiple first parents), could not be, because it would not accord with the transmission of original Sin.
When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.
Humani Generis p. 37
Only a person who generates from the line of Adam would have the stain of original in
But if anyone were to be formed by God out of human flesh, it is evident that the active power would not be derived from Adam. Consequently he would not contract original sin: even as a hand would have no part in a human sin, if it were moved, not by the man's will, but by some external power.
Summa Theologia - First Part of the Second Part, Question 81, Article 3
Jesus received His human nature entirely from his Mother and to all appearances accounts was a regular male infant, undergoing the normal "ransom" for first-born sons.
But when the fullness of time had come, God sent his Son, born of a woman, born under the law
Baptism washes away the stain of original sin and leaves a mark on the soul which lasts forever, certainly longer than the dampness of the water or the scent of the chrism
"When we made our first profession of faith while receiving the holy Baptism that cleansed us, the forgiveness we received then was so full and complete that there remained in us absolutely nothing left to efface, neither original sin nor offenses committed by our own will, nor was there left any penalty to suffer in order to expiate them.... Yet the grace of Baptism delivers no one from all the weakness of nature. On the contrary, we must still combat the movements of concupiscence that never cease leading us into evil "
Baptism, the gateway to the sacraments and necessary for salvation by actual reception or at least by desire, is validly conferred only by a washing of true water with the proper form of words. Through baptism men and women are freed from sin, are reborn as children of God, and, configured to Christ by an indelible character, are incorporated into the Church.
So if the Original Sin can only be transmitted by Adam's heirs and accords with the nature given to us from our parents - only a human nature can be transmitted - and that nature is not biological, I answer that the transmission of original sin is not a biological thing, but a spiritual pollution that only pollutes Adam's heirs; unless that heir was saved (at the moment of her conception) by an act of God.
