OK really I need an opinion I was wondering, I am escritura a story and Percy and Annabeth son has epilepsy but they don't know why. Should I make him have a tumor causing it so that he may have cancer?

Also they have another child who is a girl adn is three years old. Their son is turning six. He was born with a brain disorder that caused the epilepsy but I could make it where it starts turning into a tumor that turns into cancer and he has to undergo treatment ect. Opinion needed URGENT!!