I taught him well

I've taught my young son well.
This tea-time, my wife asked him where sausages come from.
"A pig," he answered confidently.
"Very good," she said. "How do you know that?"
This tea-time, my wife asked him where sausages come from.
"A pig," he answered confidently.
"Very good," she said. "How do you know that?"
Spoiler: