So the church believes it but doesn't actually say it's part of the doctrine. In other words, it's lay doctrine. That almost uniquely mormon set of doctrines that's entirely unofficial so it can be denied in the instances where it's embarassing.
You know, since Brigham Young and other General Authorities believed all kinds of other racist things too, and those things were much more officially codified into church policy. But those totally don't count for some reason.
IMHO, the church would be much better served if it cracked down on this kind of lay doctrine.