Moonchild, by Pat Mills and John Armstrong, was serial that ran in Misty #1-13. It concerned a girl named Rosemary Black, who lived with her abusive, old-fashioned mother (believed locally to be a witch) and was mercilessly bullied for being 'different' by her schoolmates. Rosemary discovers by accident that she has telekinetic powers, something to do with the crescent moon-shaped birthmark on her forehead, and that both the mark and the power have been passed down through the female side of her mother's family for generations (skipping her mother, whose hatred of Rosemary is caused by jealousy).
When the girl's tormentors eventually trick her into attending a 13th birthday party set up specifically to upset her, Rosemary turns the power on them and causes a house fire, but her long-lost grandmother arrives and saves everyone at the cost of her own life. Abandoned by her mother and with her power seemingly having burnt itself out, Rosemary is taken in by the parents of her friend Anne, and settles down to live a normal life (yeah, like that's likely).
Any similarities between this story and the rather better known horror movie Carrie are almost certainly in no way coincidental.
The story was reprinted in Misty (Collected Edition) Vol 1 1.