Oh oh I know something. The Abasi's are taught about magic and such at a certain age. It used to be around teenage age, but maybe one of his family did something (prankster) with Lou's older brother and after that the age was lowered, making it the "Chang rule"?

Of course they worked hard not to make sure they knew (because the parents doesn't find it chic) but maybe for fun (some of) them can know?

If this makes sense.