"Ever heard of recessive geanes?" Osiris asked. "I just learned about the whole DNA thing recently myself... though it must be slightly different fotr deities."
"Oh, well, red hair is a 'hidden' trait that Isis and I apprently both have; that means it's in our blood but it doens't show. For this Cleo, when we had her, she inherited to parts of the hidden trait, which, ah, makes a whole, so it shows up." Osiris paused. "That's the simplest I can make it; if you want more, you'll have to look it up."
"I wouldn't understand it even if I did. And if you and Isis both have red hair, that doesn't show up, then you can stop being so nasty to me about mine."
"I won't be able to now because of Cleo." Osiris said. "Here, how about a live and let live policy? I can't promise I'll be friends with you, but I won't be deliberately nasty anymore, okay?"