A missionary is sent into the deepest, darkest part of Africa to live with a tribe.
He spends years with the people, teaching them to read and write, and preaching to them about the good Christian ways of the white man.
One thing he particularly stresses is the evils of sexual sin: Thou must not commit adultery or fornication!
One day, the wife of one of the tribe's noblemen gives birth to a white baby.
The village is shocked and the chief is sent to talk with the missionary.
"You have taught us of the evils of sexual sin, yet here, a black woman gives birth to a white child. You are the only white man who has ever set foot in our village. Even Stevie Wonder could see what's been going on!"
The missionary replies, "No, no. You are mistaken. What you have here is a natural occurrence, what is called an albino. Look to thy yonder field. See the flock of white sheep, and yet amongst them, one of them is black. Nature does this on occasion."
"Tell you what," the chief says, "You never mention the sheep again, and I won't say anything about the baby."