However, the children have their moments.
The source added that William and Kate's children do bicker and that it's "usually over silly things like toys or what TV shows they want to watch."
"But most of the time they get on."
Royal fans will know that each of the royal children has very distinct personalities - a fact that isn't lost on their parents either.
In fact, the royal insider told Us Weekly that the Duke and Duchess of Cambridge have enjoyed watching.
"Charlotte’s extremely confident and loves attention, whereas George is more reserved, although he is starting to come out of his shell," the source said.
"George is always looking out for his younger brother and sister and is already showing traits of making an excellent leader."
Prince Louis is said to be a "really mommy's boy."
Recent photos of Kate in Pakistan show the Duchess sporting a small bump, sparking rumours she may already be pregnant.
What’s more, Kate showed off her maternal side when she visited a college for girls in Islamabad.
The duchess spent time chatting and laughing with the school children and was clearly in her element, suggesting she could be feeling clucky
Further adding to speculation that Kate is expecting her fourth child is the fact that the couple took a doctor on tour with them for the first time.
A medic friend of William’s from his time working with the East Anglian Air Ambulance was included in their entourage.
Given Kate’s history of hyperemesis gravidarum in the early stages of pregnancy, it wouldn’t be a surprise if the couple wanted the peace of mind of having a medic on hand.