My elder GS and I used to make a point of doing something 'naughty' when he was small. It was usually something very minor like 5 minutes extra TV, but he loved it. When DDs were young my FIL used to serve them lemonade and chocolate biscuits in the morning when we stayed. We turned a blind eye and it doesn't seem to have harmed them.
4 Years On…..Health-wise, Has Anything Changed?
To think that London, or anywhere else for that matter, does not belong to any one demographic