During a sit down chat with the BBC's Louise Minchin, the Countess shared how her eldest daughter Louise realised not all grandmothers have their own kingdom!
"It happened a little while ago," the 51-year-old answered, when asked if her two kids knew how important their granny is.
Watch the charming moment in the video player below. Post continues...
"Well for Louise, actually, it was much more of a shock to the system. It was only when she was coming home from school and saying, 'Mummy, people keep on telling me that grandma is the queen.'"
"And I asked her, 'Yes, how does that make you feel? And she said, 'I don't understand.'"
The mum-of-two continued, "I don't think she had grasped that perhaps there was only one queen."
Despite their royal ties, for Sophie and her husband, Prince Edward, they're main desire is to give their children a grounded and normal upbringing - something they have managed to do perfectly with their two kids, Louise, 12, and eight-year-old James.
"Certainly when they were very young we tried to keep them out of it," Sophie admitted, adding, "Only because for their sakes, to grow up as normally as possible we felt was quite important."
"And they're going to have to go out and get a job and earn a living later on in life and if they've had a normal a start in life they possibly can get, then hopefully that will stand them in good stead."
The royal kids recently joined their grandmother, along with her five great-grandchildren, including the two-year-old daughter of Zara and Mike Tindall, Mia, Savannah, five, and Isla Phillips three, who are daughters of The Queen's oldest grandson Peter Phillips and his wife Autumn, for a commemorative portrait session for her milestone 90th.
And of course, two-year-old Prince George and his sister, Princess Charlotte.
Relive Louise's starring role in her grandmother Queen Elizabeth's 90th Royal Portraits by clicking on the link below!
Speaking of the iconic photo, the proud mum revealed there was actually a cuter snap from the day!
"I don't think any of us knew quite what to expect. Anything could have gone wrong because we had some quite littlies in the picture! But they all behaved fantastically well," she admitted.
"I think actually the better photograph would have been the one from behind the children looking to all of the adults, trying to get all the children to smile and laugh, to look engaging and everything."
Here's hoping we see that photo one day!