There are within Christian tradition (Roman, Protestant, Orthodox) three views of the origin of the individual soul.
FIRST: Preexistence. This view as taught by Origen, maintains that souls of mankind had a conscious state in some sort of previous state. This condemns them to be born into bodies in this life. (almost sounds like reincarnation)
SECOND: Traducianism. This view teaches that the soul is generated by the two parents in the same manner as the physical charistics of the individual.
THIRD: Creationism. This is the majourity view of all of the churches. Creationism is the view that the soul is created by the direct and immediate agency of God, and is infused into the person at conception.
Of those three views, I personally favour Traducianism, as it avoids a messy problem of Creationism, namely if the soul is created by immediate agency of God, and is indued with original sin, QED, God is the source of sin! By a traducian understanding, a soul corrupted by original sin is the responsibility of the parents who were also corrupted by original sin. It also explains better the Incarnation, if Jesus had no human father, he could not have had a human soul corrupted by sin.
"The_Doc" has stated in the past that, in addition (or perhaps I should say, in correlation with) the Sin-imputation "problem" with the Soul-Creationist view identified by CDL in the post above, he feels that Traducian or "Natural generation" theology does a much better job of expositing various passages of Scripture on Human Sinfulness (Romans 1, for example) than does the Federal-Covenantal "imputation" view favored by Soul-Creationists. He sent me a very good essay on the subject at one time. I think that I lost it over the summer when my computer crashed. I should probably ask for another copy.
I wholeheartedly agree with "the_doc"s view, except that I don't see any "opposition" between Traducianism and Federal-Covenantal theology. In my opinion, Traducianism makes for a much stronger and more organically-complete Federal-Covenantal theology than the (vaguely artificial, it seems to me) "structural-inputational" formula proffered by the Soul-Creationists.
In other words, if Soul-Creationists believe in the universal inheritance of Original Sin by the entire Race of Man, then they sorta have to be Federal-Covenantal theologians. Given their belief in Soul-Creationism, the Legal Imputation of Original Sin to the Race of Man as "federal participants" in the Adamic Covenant is the only explanation available to them. So Soul-Creationists have to be Federal-Covenantal theologians.
But (IMVHO), this does not imply any opposition between Traducianism and Federal-Covenantalism; I rather think that it makes the argument for Man's federal-covenantal participation in Adam's Sin that much stronger than it could ever be under Soul-Creationism -- the Race of Man is fallen in Adam not only by imputed *legal* inheritance as federal-participants in the Adamic Covenant, but also by organic *natural* inheritance as Adam's natural heirs.