To write or not to write…in a book

We have a debate going on in my house around whether or not it’s ok to write in a book.

For whatever reason I would never write in a novel, but I write ALL OVER non-fiction. In fact, for this reason, I don’t enjoy e-books as much because, while I know I can highlight and make notes in an e-book reading app, it’s just nowhere near as satisfying.