The first man and woman had no children for a long time.

They did not know the secret of procreation and tried to have union in various ways without success. 

One day the man saw the woman climbing a tree and noticed her private parts, and so that night he sought union with her again.

She refused at first, saying that he had only seen an ulcer, but later she gave in.

She suffered great pain at this union but, in due course, she bore a son, much to the surprise of both of them.
 
That was the beginning of their family, for they had found the secret of getting children.