How is original sin transmitted?

If original sin is transmitted only through our fathers then the only answer I find is that it is through blood. We don't have the blood of our mothers and the ovum doesn't have that ability, it is through the sperm fertilising the egg that has the ability to produce blood.

Furthermore the blood of the mother and the blood no not mix although there are occasions that it will happen. So Jesus was sinless he didn't have a drop of Adams blood in his veins

Let me just quote the comments from the Moore College course (Doctrine 2):

We speak of 'original sin' in the sense that our sin arises from our origin in Adam. We are not saying that Adam was created sinful but that Adam represented all of us in his dealings with God. From his rebellion flowed death, misery, shame and suffering; from it also flowed the tendency of the human race towards evil. (p. 30)

Nathan Bunney has given the scripture references for the notion of original sin, the main one being Romans 5:12, 'Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned'. We are identified with Adam because we have our human origin in him. If we identify with Christ in his death, we are then freed from this bondage.

As to the question of "how exactly is original sin passed down to the rest of mankind", it seems believable that: 1) it is transmitted both through father and mother, because both became sinful. 2) it is transmitted both by spirit and body 3) no one knows the exact way of transmission. Why? Because the exact opposite way of restoring is also not known "The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit." (Jn 3.8). We only can see the consequences, but not the process itself. The second question: "If so, what exempted Christ from sin but allowed him to remain 100% man". Fathers of Church, namely Cyrill of Alexsandria, say that from the moment of incarnation, Jesus' body became incorruptible through the power of Almighty God who wished to be a human. This is a large topic and there is lot of literature on this. If necessary, I can cite some of them.

What is original sin?

"Original sin", in Catholic theology, refers to the natural state of deprivation of grace. So man, by nature, is deprived of the state of grace.

Because grace is no longer "natural", it can be obtained only through supernatural means - through God. So even though a man and woman may both be in the state of grace and give birth to a baby, that baby does not inherit their spiritual state, but only their nature.

Therefore, the baby, by nature, is deprived of grace. This is how original sin is transmitted.

Recommended reading: Catechism of Catholic Church on Original Sin

St. Thomas Aquinas explains it thus (Summa Theologica I-II q. 81 a. 1 c.):

According to the Catholic Faith we are bound to hold that the first sin of the first man is transmitted to his descendants, by way of origin. For this reason children are taken to be baptized soon after their birth, to show that they have to be washed from some uncleanness. The contrary is part of the Pelagian heresy, as is clear from Augustine in many of his books [*For instance, Retract. i, 9; De Pecc. Merit. et Remiss. ix; Contra Julian. iii, 1; De Dono Persev. xi, xii.]

In endeavoring to explain how the sin of our first parent could be transmitted by way of origin to his descendants, various writers have gone about it in various ways. For some, considering that the subject of sin is the rational soul, maintained that the rational soul is transmitted with the s*m*n, so that thus an infected soul would seem to produce other infected souls. Others, rejecting this as erroneous, endeavored to show how the guilt of the parent's soul can be transmitted to the children, even though the soul be not transmitted, from the fact that defects of the body are transmitted from parent to child—thus a leper may beget a leper, or a gouty man may be the father of a gouty son, on account of some seminal corruption, although this corruption is not leprosy or gout. Now since the body is proportionate to the soul, and since the soul's defects redound into the body, and vice versa, in like manner, say they, a culpable defect of the soul is passed on to the child, through the transmission of the s*m*n, albeit the s*m*n itself is not the subject of the guilt.

But all these explanations are insufficient. Because, granted that some bodily defects are transmitted by way of origin from parent to child, and granted that even some defects of the soul are transmitted in consequence, on account of a defect in the bodily habit, as in the case of idiots begetting idiots; nevertheless the fact of having a defect by the way of origin seems to exclude the notion of guilt, which is essentially something voluntary. Wherefore granted that the rational soul were transmitted, from the very fact that the stain on the child's soul is not in its will, it would cease to be a guilty stain binding its subject to punishment; for, as the Philosopher says (Ethic. iii, 5), "no one reproaches a man born blind; one rather takes pity on him."

Therefore we must explain the matter otherwise by saying that all men born of Adam may be considered as one man, inasmuch as they have one common nature, which they receive from their first parents; even as in civil matters, all who are members of one community are reputed as one body, and the whole community as one man. Indeed Porphyry says (Praedic., De Specie) that "by sharing the same species, many men are one man." Accordingly the multitude of men born of Adam, are as so many members of one body. Now the action of one member of the body, of the hand for instance, is voluntary not by the will of that hand, but by the will of the soul, the first mover of the members. Wherefore a murder which the hand commits would not be imputed as a sin to the hand, considered by itself as apart from the body, but is imputed to it as something belonging to man and moved by man's first moving principle. In this way, then, the disorder which is in this man born of Adam, is voluntary, not by his will, but by the will of his first parent, who, by the movement of generation, moves all who originate from him, even as the soul's will moves all the members to their actions. Hence the sin which is thus transmitted by the first parent to his descendants is called "original," just as the sin which flows from the soul into the bodily members is called "actual." And just as the actual sin that is committed by a member of the body, is not the sin of that member, except inasmuch as that member is a part of the man, for which reason it is called a "human sin"; so original sin is not the sin of this person, except inasmuch as this person receives his nature from his first parent, for which reason it is called the "sin of nature," according to Eph. 2:3: "We . . . were by nature children of wrath."

One can hold that there is indeed Original Sin without assuming the nature of man changed. One might say instead, that the image of God was marred in man, like a coin covered in dross and scored with cuts. But the image remained. The nature - how man was made - did not differ, but his mode - as the Fathers say (I'm leaning heavily on Maximus the Confessor here) changed with the fall. So he operated as a beast though he was a man.

It follows therefore that reproduction - and not only physical reproduction but also parentage through fallen adoptive parents - transmits not merely the effects of previous sins on the bodies and souls of the children and parents, but also re-imprints the patterns and habits which foster the disease.

It then therefore follows, that God had to raise up righteous seed - those who were free from habitual sin and receptive to God's help - and that these, and in particular the Mother of God - could and would be able to accept the Son of God as a child and raise him.

This except gives an idea of the Orthodox position vis a vis 'sinful nature':

...Every created nature is made to live in communion with God. Human nature itself lives in communion with God. Our fall does not consist in becoming something other than human – we have yet to become truly human. Thus St. Paul says: “Man is the glory of God” (1 Cor. 11:7). And St. Irenaeus says, “The glory of God is man fully alive” (Adv. Her. 4.34.5-7). Our becoming truly human would mean the restoration of our true integrity – we would live in accordance with our nature and praise the Lord without ceasing. The natures of all creation ceaselessly praise God by their very existence. Our struggle is to rejoin the song of creation with the whole of our being.

http://fatherstephen.wordpress.com/2012/05/02/all-dogs-go-to-heaven/

So it is not the nature that changes, but whether those hypostases - concrete individuals - live in accordance to how they were made. Original sin constitutes a departure from this way of being at the very outset of human existence that affects the lives of every descendent of Adam and Eve.

I think that the best answer here is that the Scriptures are not entirely clear on how original sin is transmitted. One thing that we do know (or believe the scriptures to teach) is:

The sin nature is passed on to us from our fathers and not our mothers

• Sin entered the world through Adam - Romans 5:12 - not Eve who sinned first.
• More directly taught in Heb 7:9-10
• Christ Who did not have an earthly father did not have original sin passed to Him.

That is about all that we know (and even this view is heavily disputed.)

Other good questions: Is it genetic (I doubt it) or spiritual (much more likely)? What would happen if we used two women's DNA to clone a new person, if the new creation had a soul would it be sinless?