Thanks everyone. This is very helpful. Zach Dunn, “immaculate conception,” duh, I should have seen that. I guess I was to busy looking at the forest to see the trees. In any case, I appreciate the insight.
PJM, I have always understood Scripture to teach that sin entered the world through Adam’s disobedience and, as such, corrupted the nature of man. Furthermore, this corruption (disease) has been passed down from Adam, if you will, as part of our spiritual genetic code. But what you are saying is that God, at conception, makes each person a sinner by executive fiat. Is this correct? And, if so, is this the teaching of the Church?
I would respectfully disagree with PJM’s articulation (sorry

). I wouldn’t call Original Sin something that God “imposes”. I have never heard it described that way before. Rather, Original Sin is something that has become part of human nature in light of us being all one human family descended from Adam and Eve.
Perhaps your best bet would be to look at how the Catechism of the Catholic Church (CCC) describes Original Sin. That is a more authoritative source than any of us here.
CCC 385-421 is probably the best bet. In particular, look at CCC 404-405:
404 How did the sin of Adam become the sin of all his descendants? The whole human race is in Adam “as one body of one man”. [293] By this “unity of the human race” all men are implicated in Adam’s sin, as all are implicated in Christ’s justice. Still, the transmission of original sin is a mystery that we cannot fully understand. But we do know by Revelation that Adam had received original holiness and justice not for himself alone, but for all human nature. By yielding to the tempter, Adam and Eve committed a
personal sin, but this sin affected the
human nature that they would then transmit
in a fallen state. [294] It is a sin which will be transmitted by propagation to all mankind, that is, by the transmission of a human nature deprived of original holiness and justice. And that is why original sin is called “sin” only in an analogical sense: it is a sin “contracted” and not “committed” - a state and not an act.
405 Although it is proper to each individual, [295] original sin does not have the character of a personal fault in any of Adam’s descendants. It is a deprivation of original holiness and justice, but human nature has not been totally corrupted: it is wounded in the natural powers proper to it, subject to ignorance, suffering and the dominion of death, and inclined to sin - an inclination to evil that is called “concupiscence”. Baptism, by imparting the life of Christ’s grace, erases original sin and turns a man back towards God, but the consequences for nature, weakened and inclined to evil, persist in man and summon him to spiritual battle.
[293] St. Thomas Aquinas, De Malo 4,1.
[294] Cf. Council of Trent: DS 1511-1512
[295] Cf. Council of Trent: DS 1513.