According to Ancestry.com, the sisters are direct decedents of King Edward III, who ruled England from 1327-1377 and whose reign saw the start of The Hundred Years' war between England and France.
The two are also related to Kate Middleton and are distant cousins of the Duchess of Cambridge (Elle is Kate's 21st cousin to be exact).
No wonder the 16-year-old beauty is perfect to play Princess Aurora in Maleficent!
Middleton and the Fanning girls both descend from King Edward I aka "Longshanks", who served as the King of England from 1272 to 1307.
Additionally, Middleton's mother, Carole, is a grand-daughter of King Edward III, providing yet another link between the brunette royal and the on-screen princess.
"Generation after generation, the lines we looked at pieced back directly to King Edward III proving that Elle is a direct descendant of royalty," Michelle Ercanbrack, a family historian for Ancestry.com, told People. "You can consider her a long lost princess. This connection is so unique and rare."
The Fanning girls aren't the only ones in Hollywood with a surprising connection to Kate. Ellen DeGeneres is also a distant cousin of the royal.