The Duke and Duchess' strict rules includes a no-shouting policy, never going to bed mad, and banning all TV before tea-time.
A royal source revealed that "shouting is absolutely off limits" for the Cambridge children at all times.
Instead, the kids are encouraged to discuss what it is that's bothering them in a more constructive manner.
The source said: "The children are encouraged to talk about their feelings.
"They express their concerns over school subjects, a swimming class, a tricky ballet manoeuvre, a missed tennis rally, or seeing children starving on a TV ad. But a talk ensues and a solution found," they added to Fabulous.
It was also revealed that Kate and William follow one of the rules and do not shout themselves in order to put on a “united front” for their three children.
"There is no question of one parent saying 'no' and the other saying 'yes' later on as Kate and William want to present a unified parental front to their children," the source added.
William and Kate also never let the kids go to bed angry and encourage the three of them to always talk about their feelings.
"Emotional coaching is a Cambridge parental building block," the source said.
"Awareness of others less fortunate than themselves, physical and mental health and going to sleep in a calm happy house is so utterly important to them all."
Since they decided to spend lockdown at their Norfolk home Amner Hall, the family have settled into a new routine - which involves none of them watching television until they have had their tea.
"The television is not on throughout the day and programmes have to be met with parental approval," the source continued.
When they are allowed to watch the television, Prince George and Princess Charlotte are said to be fans of CBBC's What, Where, When, Why, Numberblocks and Horrible Histories - which "is a bit advanced but they love it".
The source added: "There is the staple of Peppa Pig, Thomas the Tank Engine and cartoons on Disney Channel.
"All the children seem to like games and a quiz," the insider said. "They get fired up [trying to find things from the show] in the garden."