The only things more iconic than Wolverine’s crazy devil horns hairdo are his razor-sharp claws. He’s sliced and diced his way through countless villains over the decades, and his latest movie outing, the R-rated Logan, is his most violent yet. However, Logan isn’t the only mutant in the Marvel universe with claws.

He’s joined in the new flick by newcomer Laura Kinney, a young mutant who goes by X-23 in Marvel comics. Laura has Logan’s healing factor and six adamantium claws, but hers are surgically planted in different places — instead of Logan’s three per hand, she has two, plus an additional claw in each foot. Why the difference? Well, it’s a little complicated.

In the movie, which is loosely based on a couple different Marvel comics storylines, Laura was created in a lab by the shadowy corporation Transgiene. Almost all of the real mutants in Logan’s dusty future are gone, but Transgiene’s scientists are trying to force mutated kids into becoming weapons. They create Laura using some of Logan’s DNA, and she inherits his healing factor. Then the scientists insert three adamantium claws in her hands and feet in what looks like a truly horrific surgery.

At one point in the film, Patrick Stewart’s Professor X guesses that Laura has claws in her feet because she’s essentially the female version of Logan’s unique “species.” As the Professor puts it, female animals often use their back feet as weapons. Hence, Laura has deadly, sharp kicks.

Professor X’s logic doesn’t really track for a couple reasons, however. His claim that female animals have sharper claws on their legs is dubious. The bigger problem with his thinking is that Laura’s claws were artificial, having been implanted by Transgiene’s ghoulish scientists.

However, Laura’s claw placement made a little bit more sense in the comics. She was created in a lab, like in Logan, except on the page she was intended to be a recreation of Weapon X. The scientists behind the project wanted to just make a straight-up clone of Logan. However, their genetic sample is damaged, and they can’t use Logan’s Y chromosome. Instead, they duplicate the X chromosome, creating Laura. She, like Logan before her, has natural bone claws. The same dubious rationale, that females in the animal kingdom use their legs as weapons more often, explains why two of her six claws are located in her feet.

Even if the real life science behind the gender difference is bunk, the comics version of Laura makes a certain amount of sense. She naturally has bone claws inside her feet (and the horrible scientists ripped them out without anesthetic, coated them in adamantium, and then reinserted them). In Logan, the claws are totally artificial, so the real reason she has them between her toes is because that’s how Laura looks in the comics.

That’s totally fine, because it’s a pretty badass look.

That's not how spines work, though.

Logan hits theaters this Friday.

Photos via Marvel, 20th Century Fox