“Her perfect smile is often swapped for the kind of open-mouthed, face-wrinkled laughter of what looks like genuine humour and delight and this is one of the best examples of that body language ritual.”
Her relaxed demeanour in the relationship may have had an influence on how Prince William acts also.
“William has often looked more serious and formal,” the expert continued.
“He adopts his signature fig-leaf pose with hands in a self-conscious barrier gesture in front of his pelvis.
“But now he is not only laughing with his wife, he also seems to be winding her up here too, and that sense of playfulness suggests very strong bonds.”
source: express.co.uk