A missionary gets sent into deepest, darkest Africa and goes to live
with a tribe therein. He spends years with the people, teaching them
to read, write and the good Christian ways of the white man. One thing
he particularly stresses is the evils of sexual sin. "Thou must not
commit adultery nor fornication!!" he preached incessantly.

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

"You have taught us of the evils of sexual sin, yet here a black woman
gave birth to a white child. You are the only white man that has ever
set foot in our village. It doesn't take a genius to work out what
has been going on!"

The missionary replies: "No, no, my good man. You are mistaken. What
you have here is a natural occurrence - what is called an albino. Look
to thy yonder field. See a field of white sheep, and yet amongst them
is one black one. Nature does this on occasion."

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