Mom looks at you in shock. "How is this possible. Jack? Did he give John his book" She thinks back, and remembers her older brother. He was older than her by 14 years and the two weren't close due to the age gap. The distance increased as she and her sister, Catherine, learnt they had magic powers, and that Jack didn't. Eventually, after attempts by her and Catherine to try and have a closer relationship, by the use of magic, failed, and it tore her family apart. Unknown, Jack had taken a magic book from Catherine, and during the years of isolation, he learnt how to mimic his sisters' magic, eventually writing a book intendical to Catherine's.
However he did made contact in the last 3 months of his life, and both, she, he and Catherine parted on good terms, especially after he revealed his secret, though both your aunt and Mom thought the secret of how he maninulated magic, although highly unstable, (though Jack never knew this) as a guy, died with him. During this time, he was pleased that you had a relationship he never did, give you his book, with the intent that you learn who to protect yourself so any mischief from your sisters can be stopped, and that knowing you can respond to them, might prevent history from repeating itself. He also indicated that you shouldn't keep your secret hidden away forever, just until you can protect yourself.
Now Mom sees that it didn't die, and that you've got it, and by the looks of it, your 'magic' is fairly advanced. She started to panic, since she knows that unlike her brother, you're are a twin to a witch, and you're practising psudo magic...