This is just in from deepest, darkest, er, Australia, actually, and I thought you deserved it:
A missionary was sent to the deepest, darkest part of Africa, and moved in with a primitive native tribe. He spent several years with the people, during which he particularly stressed the evil of sexual sin... no adultery, no fornication!
One day, the wife of one of the tribe's noblemen gave birth to a child.
But the child was white! This caused quite a stir in the village. The chief sent for the missionary, and said, "You have taught us the evils of sexual sin, but here is a black woman who gives birth to a white child. And you are the only white man in a distance of a five days walk! What is the explanation?"
The missionary replied, "No, no, my good man - you're mistaken. This is a natural occurrence, what in English we call an albino. Nature does this on some occasions. For example, look over there at that flock of sheep. They are all white, except -- look, there is one black sheep among them! Could you explain this to me?"
The chief thinks it over for a while and then replies, "Okay. I'll tell you what, father. You don't say anything about the black sheep, and I won't say anything about the white child."