The Duke and Duchess of Cambridge's son Prince George always wears shorts - a tradition in the Royal Family - but Meghan is "determined" to not have her children wearing them.
A source tells the publication: "She's determined her child won't be paraded around in little shorts like Prince George."
William Hanson, an etiquette expert, claims trousers are deemed “suburban”.
He said while he doubts there "would have been a memo sent around Kensington Palace telling George to wear shorts", Kate would be aware of clothing protocol.
Hanson added: "I don't think that the sartorial rule of shorts for young boys would be a new one for Catherine.
Hanson told The Sun, “Not only does The Duchess of Cambridge have to worry about dressing herself but she has to dress her own children appropriately.
"She has to find a balance between royal tradition, heritage and more proletariat customs, such as the ‘suburban’ habit of making young boys wear trousers."
"I bet her brother James wore shorts as a boy and Sophie Wessex has dressed her son in a similar fashion."