I had always attributed it to bad luck in the genetic lottery. I am three-eighths Welsh and a quarter Scottish, which is a rotten mixture: part Cavalier, part Roundhead. This means that every pleasurable experience I have in life is coloured by Calvinist guilt: in the remote likelihood that I were ever to find myself sitting in the grotto in the Playboy Mansion, my Welsh part would enjoy it while the Scottish part would be worrying about how much it cost to heat.