Everyone knows that when a human baby is conceived, its body is produced by a biological process combining the physical characteristics of its parents.  Since the double helical pattern of the DNA molecule was discovered, science is actually able to give a fairly accurate explanation of exactly how this happens.  But what about the immaterial part of the person, the soul?  Are parents responsible for that?  Here we leave the realm of science and enter the realm of theology (realms that are only formally distinct, I hasten to add).

There are essentially three opinions that have developed over time with regard to the origin of the soul.  The first is known as pre-existence and is associated most closely with the ancient theologian Origen from Alexandria in Egypt.  Origen taught that all human souls were divinely created at some point in the past and are held in storage, sort of, until a new body is propagated, when God then places one of them into it.  This opinion owes a good deal more to Greek philosophy than to the Bible-though it was known among some ancient Jewish groups-and has never had much support in the Christian church.  Not so with the other two positions, though there is no explicit biblical support for either.  Both are deductions from biblical teaching.

Some have held that as the parents create the body of a child, so they also create the soul.  This position is known as traducianism.  One of the ancient proponents of this view, Tertullian, held that the soul, and indeed all non-material things, have substance, hence it can be propagated just like the body.  Not all who advocate this view hold that position, however.  This has been criticized by some because it makes parents creators, a role belonging only to God.

The third option, creationism, holds that God creates each individual soul and unites it with the developing body.  This view has been criticized because it means that God is still creating, although he is said to have rested from that after six days in Genesis.

Traducianism by definition holds that the soul and body are joined together at conception.  Neither is ever independent of the other.  Creationism, on the other hand is indefinite as to the time of ensoulment.  It could be at conception or as late as the first breath, (arguing from Genesis that man became a living soul only when God breathed into him the breath of life), or at some time between.  Those who argue, for example, that the life of the flesh is in the blood, would see ensoulment happening when the blood system develops in the fetus.

Where one lands on this question can affect what one thinks or how one argues about abortion.  If traducianism is true, then all abortions kill unborn babies, who are personally complete.  On the other hand, if ensoulment is the result of an unknown and undefined act of God, then it would be possible to argue that at least some early abortions do not take life and are legitimate.

There have also been interesting questions raised about the incarnation of Jesus relative to this point, though we cannot pursue them here.