Where do we read that? Then what we get from our parents is only the body? If God, Himself, directly and individually, creates each person’s soul at conception how can there be original sin? Doesn’t make sense.
Our human nature is an unique unification of both our spiritual soul and our material body. Our human nature shares in the image of God precisely because it is animated by a spiritual soul. This unity of soul and body is profound. Because of the God created spiritual soul, the body made of matter becomes a living human body at conception. Consequently, there is a whole human person at conception. Yet, the human person is not two natures united, but rather the union of the spiritual and material forms one, single nature.
Being the first human beings, Adam along with his spouse Eve were immediately established in friendship with God, their Creator. They were in the state of original holiness and justice-- which means that they were sharing in the life of God (known today as the state of Sanctifying Grace) and they had harmony within themselves.
Properly speaking, Original Sin is the act of the original human Adam. Adam’s act of scorning his God broke his original relationship of holiness in friendship with God. This changed Adam’s state of being in that his human nature was deprived of original holiness.
Catholicism teaches that the whole of humanity is in Adam “as one body of one man”. (paragraph 404,
Catechism of the Catholic Church, Second Edition.) Adam’s human nature would be transmitted by propagation to all his descendants: "By this “unity of the human race” all men are implicated in Adam’s sin, as all are implicated in Christ’s justice. St. Paul teaches this in Romans 5: 12-21. Flat out, the *Catechism *says: “Still, the transmission of original sin is a mystery that we cannot fully understand.”
What we know is that “Original Sin” is not a personal fault in any of Adam’s descendants. Our nature begins in the state of deprivation of original holiness, but it is not totally corrupted. The Sacrament of Baptism, by imparting the life of Christ’s grace, removes this state of deprivation and returns us to the state of Sanctifying Grace, God’s presence, original holiness, within us.
Paragraphs 362-366 of the* Catechism of the Catholic Church, Second Edition* explain the soul. Paragraphs 396-409 explain Original Sin.