According to royal commentators, Kate Middleton is known to have a collected and composed nature, both when it comes to attending various events and when dealing with Prince George, Princess Charlotte, and Prince Louis.
With the kids growing up and showing up more at royal engagements, they are observed to be well-mannered and well-behaved most of the time. But if there are ever instances of misbehaviour, apparently Kate does not publicly scold them but instead resorts to what can only be described as quiet discipline.