A Question of Loyalty

[Eönwë]

Originally Posted by Formendacil

But (and as we stray from Tolkien to genetics, I admit my knowledge weakens), my understanding is that chromosomes come in pairs. Did Morgoth just tag ONE chromosome with the sun-pain, and then breed it into his orks? It certainly seems easier than hitting EVERY chromosome in that slot, and if sun-pain is a dominant gene, then once Morgoth had done enough breeding, practically every ork would hate the sun (quite apart from cultural pressures put on by the Dark Lord's antipathy, together with Sauron, the Balrogs, the Dragons, etc...).

But why would Morgoth want to make his orcs weaker by making giving them "sun-pain"? It seems to me to be a side-effect of the orc-making process rather than one of the features. Or maybe being deep underground made them mutate to having low levels of melanin in their skin in order to create as much vitamin D as possible, and then when they finally got out into the sun, it was too much.

Or am I totally wrong here...?