Of course, if you think that the human soul is actually just biochemical reactions in the brain . . .
Actually, I'm quite big into the human soul. I also know that the human soul doesn't have anything to do with the genetics that determine our physical and related traits. After all, we KNOW from experience that there are some people who are just plain smarter than others. This doesn't mean that they have "better" or "bigger" souls than the other, however. Our soul is immaterial. Intelligence IS biochemical and physiological, as well as being partially environmental. Intelligence doesn't equal "the soul", however.
Since an operation on the brain can completely change a person's personality (not his intelligence, but his entire personality), then all good proponents of reductionistic science should deny the existence of a spiritual soul as being pre-modern superstition.