Offsetting the answer into the world of pigs is a really useful mechanism, in that it softens the nature of what you're about to say, which can be alarming to an 8 year old. After all, nothing like his stuff happens in the Lego movie.
'So is it the same in humans?' he asked.
'Yes,' I replied in my best pragmatic manner, whereupon I could see him making some quick calculations in his head.
'So you've had to do that twice?' he said.
I know that you're not supposed to laugh when having a discussion of a sensitive nature with your child, but I'm afraid that's the point at which I lost it.