His family tried to hide the fact, but once he had gotten older and had accidentally summoned a working pocket watch for his father's birthday, the Ministry got involved. It had taken a lot of talking from his father with the Ministry to convince not punishing Jax, nor send him to Hogwarts. But eventually, they gave in, with explicit instructions that his father teaches him to use and control his magic and to not at any circumstances use it outside the house. He was also required to give a report each week. And so Jax slowly learned how to manipulate his magical powers, the family had to move out in the middle of nowhere and have their lessons in the dead of night to not rouse suspicions.
That is, until one night, as he was walking the streets of London by himself, a muggle mugger showed up and stabbed him. Unable to contain his anger and in pain, he had casted a spell at a river nearby and summoned a Water Elemental. It was not soon after that the Ministry had caught wind of it and sent Elena Jangleton. With her help, Jax was able to stop the Water Elemental from causing too much damage and erased the mugger's memory of what had happened that night.