"Here we have two different strings of DNA. Does anybody know what makes them different?", a calm voice asked, while he showed two plastic DNA models to the students in his class. A young woman with long red hair raised her hand in the air. "Yes, Jean?"
"The model on the right has the X-Gene," she answered. "That is correct," the teacher, known as Charles Xavier, said. "And what is that special gene responsible for-" Charles was interrupted by a knock on the door. "Professor," an old-looking black-hair woman said, who stood at the door opening of the classroom, "May I interrupt please?" 
"Of course madame Calverley, how can I help?" The eleven students in the classroom, aged between 10 and 18, all looked at the door, where miss Calverley and a boy were standing. "Dan Finley has arrived today, can he join this class?" Charles' colleague asked. "Of course. Please mister Finley, take a seat," Charles nicely offered and pointed to an empty seat next to Logan. "Logan, as Dan Finley is new at this school, would you please be kind and show him around today?"