Who told you these things? That has never been the doctrine of the LDS Church, nor have I ever heard it offered as a speculation or theory.
The closest theory I could think of was one that claimed that descendants of Ham were "fence-sitters" during the War in Heaven, and that was why they were cursed while upon the Earth.
However, not only was that theory completely destroyed by the leaders of the LDS Church (who claimed that there were no fence-sitters during the War in Heaven), but the false theory itself never made the claim that descendants of Ham were destined for Hell.
Latter-Day Saints reject the ideas of predestination, to either Heaven or Hell, and believe that all people have the potential to enter into God's Kingdom.