Like it depends on what kind of magic or gifts your parents have. People can't just pick up a new magical ability on a whim.

[ she doesn't want to imagine what kind of world it would be if any demigod could learn to control the ocean because they felt like it. though she doesn't get the sense the magic here is anything like controlling the elements like big three kids. ]

We definitely don't have books angry about misplacement like this either.