I read this from a Chinese web page full of ghost stories ...
A married couple, with a young son, was always fighting, bickering, you name it. One day out of pure rage, the father murdered the mother. He hid his crime well, no one suspected anything. But he noticed something strange about his son. The boy never complained about the absence of his mother.
"Son, why aren't you calling out for Mommy? Most little boys would want their mommy to be with them. Tell me what's bothering you."
The little boy replied, "I'm fine. I was just curious why you're always carrying Mommy on your back."