In one experiment involving puppets, babies aged six months old showed a strong preference to ‘good’ helpful characters – and rejected unhelpful, ‘naughty’ ones.

In another, they even acted as judge and jury. When asked to take away treats from a ‘naughty’ puppet, some babies went further – and dished out their own punishment with a smack on its head.

They suggest that the difference between good and bad may be hardwired into the brain at birth.