Tatiana and Krista Hogan are conjoined twins. But not only that, they are joined at the head, an extremely rare occurence that’s resulted in the girls sharing parts of their brains with each other.

Neurological studies have stunned the doctors. Tatiana can see out of both of Krista’s eyes, while Krista can only see out of one of Tatiana’s. They also share the senses of touch and taste and the connection even extends to motor control. Tatiana controls 3 arms and a leg, while Krista controls 3 legs and an arm.

Amazingly, the girls say they also know one another’s thoughts without needing to speak. “We talk in our heads” is how they describe it.

Despite their unique connection, the twins remain two distinct people. Tatiana is talkative, outgoing and high-strung, while Krista is quieter, more relaxed and loves to joke. But she has a temper and can be aggressive if she doesn’t get her way.

When they were little, they used to try to pull their heads apart. Their mother always told them they were stuck, so they would have to work things out. But as they’ve gotten older and the frustrations mount, they still fight. As they freely admit, some days they don’t like being together. “She’s annoying,” says Tatiana, who promptly gives her twin a reassuring hug.