Which is what the Mormon church said until 1978 in citing the Curse of Cain (as Brigham Young did) when they refused to allow blacks to become priests (in a religion where nearly every married man or otherwise head of household is a priest, and only priests are capable of attaining exaltation). Read up on the 1978 "Revelation on Priesthood" in the Mormon church, if you get the chance. It's hilarious in it's utter shamelessness (making it a worthy successor to Joseph Smith's original gonzo "revelation").
These sorts of things are bigotry, pure and simple. Pointing to a sacred book as the source of it is nothing more than cowardly excuse making, a way for small people to avoid taking responsibility for what they believe.