I'm a big fan of this series, Jules. You might find this infamous and terrible quote from the Mormon prophet Brigham Young noteworthy as you dig for examples of spiritual eugenics: "Shall I tell you the law of God in regard to the African race? If the white man who belongs to the chosen seed mixes his blood with the seed of Cain, the penalty, under the law of God, is death on the spot. This will always be so." (March 8, 1863.) Journal of Discourses 10:110.

It's certainly a stain on LDS history, integrated from the broader U.S. cultural racism.

Looking forward to reading more.