After their baby was born, a panicked Japanese father went to see the obstetrician.
"Doctor," he said, "I don't mind telling you, but I'm a little upset because my daughter has red hair.
She can't possibly be mine."
"Nonsense," said the doctor. "Even though you and your wife both have black hair, one of your ancestors
may have contributed red hair to the gene pool."
"It isn't possible," the man insisted. "We're purely Asian."
"Well," said the doctor, "let me ask you this. How often do you have sex?"
The man seemed ashamed and he hung his head. "I've been working very hard for the past year. We only
made love once or twice a month."
"There you have it!" the doctor said confidently. "It's just rust!"
