Jean Grey is the youngest daughter of Elaine Grey and Professor John Grey. She and her older sister, Sara, were raised in a farmhouse near Bard College in Annandale-on-Hudson, New York, where her father taught History. When Jean was ten years old, she was playing with her best friend, Annie Richardson, who was accidentally hit by a car. The stress awakened Grey's mutant telepathic powers which empathically linked her to her dying friend. The traumatic experience of Annie's death left Grey in a withdrawn and deeply depressed state. Moreover, not being able to control her newly awakened telepathic abilities forced her to isolate herself from other people to hold on to her sanity.

To combat this, Jean was privately tutored by Charles Xavier in the use of her psychic abilities. But Magneto, seeing that her immense potential could help in his cause, tried to force her to join him. Xavier pleaded with Jean's father to let her to come to the institute, where she would be safer. Though her father objected, Jean was willing to go after she saw you with the professor.

As part of the original X-Men, most of their encounters were with Magneto, who was still bent on forcing Jean to join him. When Magneto attempted to kill you, she almost killed his and became almost obsessively protective of you and began to use her psychic powers to contact you in your dreams.