John J. Stewart uses Lamanites as a case study in curse-by-darkening.
John J. Stewart, Mormonism and the Negro (Orem, UT: Bookmark, 1960), 37
In scripture we read of quite a number of instances of God's placing a curse or mark upon a certain person or people because of their misconduct and disobedience to His laws. The curse usually involves not only that particular person or generation of people, but their posterity as well. One example is the Jews, cursed to become "a hiss and a byword"; another is the Lamanites, whose skin was turned dark, and that of their children after them.
Would it be justice on the part of God to just haphazardly or arbitrarily assign certain spirits to be born into these families or nations, just for the sake of carrying out His curse upon the guilty party? Or would He assign those souls whose performance in the spirit world warrants such a circumstance of birth? Which is in keep- ing with God's attribute of justice? Which is reasonable?
Think of the millions of spirits born into the Lamanite race after the Lamanites had become a fallen people. How can you justify such an unfortunate circumstance of birth except on the basis of individual performance in premortal life?