I was sat on the Tube the other day opposite a bloke in shorts who had ‘Mum’ tattooed on one knee, and ‘Dad’ tattooed on the other.

I don’t have any tattoos but I’m often curious about other people’s. Why did he have those on his kneecaps specifically? How did he he decide who got the right knee and who got the left?

If I wasn’t quite so English I might have asked