The former One Direction star made history when he became the first man to get a solo cover for the fashion magazine on its December 2020 issue.
Harry, who was photographed by Tyler Mitchell for the shots, could be seen frolicking in a field in a few fancy gowns on the cover and inside the pages.
And Anne reckons the singer's care-free attitude to gender norms when it comes to clothing comes from her.
She spoke to Lorraine Kelly on her ITV show on Tuesday and said: "I think maybe I had something to do with it.
"I was always a big fan of doing fancy dress with them [Harry and sister Gemma] when they were smaller, which Gemma hated but Harry always embraced.
"But who doesn't love dress up?"
Anne said her kids are both still the same despite gaining fame, as Gemma Styles is a writer and has a new podcast.
She said: "Harry's just... well... he's just Harry, really. He's always been Harry."
With the coronavirus pandemic and associated restrictions still going on, Anne said she's unsure about whether or not she'll get to spend Christmas with her kids.
"I'm hoping so," she said, "who knows?
"We just don't know what's going to happen, but I'm just keeping my fingers crossed.
"It'll be a very different Christmas if I don't get to see them."
But whether or not she does get to see them, there'll be plenty of turkey and trimmings for Anne.
She laughed: "They're both vegetarians now, so I'm the only one who eats turkey."
While her boy has made history as a solo male Vogue cover star, it's not the first time he's played with gender norms in his styling.
The 26-year-old has worn a women's Marc Jacobs suit before, as well as a lace collar and pair of Mary Jane shoes on this year's BRITs red carpet.
Lorraine airs weekdays at 9am on ITV