A missionary gets sent into the deepest darkest Africa, and goes to live with a tribe there. He spends years with the people, teaching them to read, write, and the good Christian ways of the white man. One thing that he particularly stresses is the evil of sexual sin.

"Thou must not commit adultery or fornication!!!"

One day, the wife of one of the tribes's noblemen gave birth to a white child. The village is shocked, and the chief is then sent by his people to talk with the missionary.

"You have taught us of the evils of sexual sin, yet here a black women gives birth to a white child. You are the only white man that has ever set foot in our village. I know what you've done!"

The missionary replies: "Oh, no, my good man - you are mistaken. What you have here is a natural occurrence, called an albino. LOOK IN YONDER FIELD! You see a field of white sheep, yet amongst them is one black sheep. Nature does this on occasion."

The chief pauses a moment, and then says, "Tell you what - you don't say anything about the sheep, I won't say anything about the kid."