Though it has been more than 20 years since the first Harry Potter book was published, it seems that not a day goes by where fans aren't still discovering new information about the series’ characters and histories. Author JK Rowling shocked fans worldwide in 2007 when she confirmed that Headmaster Albus Dumbledore was gay, for example, and she has continued to reveal important bits of information about the series over the years.

Now, a new theory gaining some traction has to do with the real reason why Harry has a lightning bolt-shaped scar on his head (though Rowling hasn't weighed in on it yet).

In a tweet, Today Years Old claimed the mark is actually linked to the Avada Kedavra curse—a.k.a. the Killing Curse—that Voldemort used in attempt to kill Harry when the boy wizard was just a baby wizard.

The account tweeted a screenshot from the Harry Potter Wiki entry about the spell, which lists information about the Killing Curse, including the hand movement used to complete it. The tweet shows that the hand movement for Avada Kedavra looks eerily like the lightning bolt which appears on Harry’s forehead throughout the films.

Harry’s scar appeared the moment the Dark Lord used the spell against him and his parents, so we already know that the Avada Kedavra and the mark have a link (and that the scar itself linked Harry to Voldemort). Whether the shape is based directly on the movement, however, is up for debate.

Some Harry Potter fans have been stunned by this new revelation, wondering how they never noticed the similarity before. But others have been quick to dismiss the claim, declaring the similarity in shape to be pure coincidence—or denying that there's a resemblance between the two shapes in the first place.

If history tells us anything, it's that it won't be long before Rowling herself decides to set the record straight.