George, once more you surprise me with a very smart remark!
The capacity to sin in each human person emerges at the very moment of her generation by God, that is, the instant when God creates a spiritual principle (“soul”) to animate a piece of “flesh” (biological stuff originating through evolution) and a human personal body appears.
At the instant the “soul” starts animating the biological stuff, the evolutionary “frailty of the flesh” and “selfish tendencies” become spiritual vulnerability to sin (“concupiscence”, in the sense of 1 John 2:16). The “neuro-psychological weakness of the human body” results from the weakness of the “soul” (intellect and will) to master the “evolutionary background” and handle according to the principle of love. But we do NOT sin because of this weakness (otherwise God would be the author of sin, what is absurd), but because we freely decide to sin, tempted by “selfish evolutionary tendencies” (1 John 2:16).
Accordingly, what is passed on genetically is the “selfish evolutionary background”, by contrast the “spiritual vulnerability to sin” emerges at the very moment of the generation of the person.
In this sense what you call “vulnerability to sin” is nothing other than “the stage of need of Redemption” (the so called “stage of original sin”). Hence, the “original sin’s transmission” does NOT happen genetically, it happens at generation.
Actually I am getting the impression that we all basically agree to the preceding points in this post, and the real point of disagreement may be that additionally I support the following position:
Before the first sin was committed, God empowered the human “souls” (i.e.: personal bodies) with so called “original Grace” (“original Blessing” in Albert’s wording) so that temptation could only be of spiritual origin, and sin could only be sin of pride.
Thanks in advance for commenting.