Philippines - Should Meghan Markle be worried that the world will soon discover the juicy secrets of her childhood? It seems so, as her half-brother, Thomas Markle Jr., is planning to reveal exactly that in a new book.

The 58-year-old retired to the Philippines with his and Meghan's father, where he says he now has enough time to work on a tell-all book about his estranged 43-year-old sibling.

The details must really be something, as Thomas told the Mirror that the book will "be swooped up real quick" once he's done writing it.

"It's coming out," he declared.

But Thomas isn't planning on stopping at a single book – with the first publication, he hopes to create the foundation for further projects.

"It's gonna be good. I really want to maybe spin off the book, then when the book gets read, the documentary will follow," he said.

Still, Thomas clarified that he isn't "greedy," adding that "it's not about the money, it's about the principle."

Despite that declaration, Thomas admitted that he wouldn't be disappointed by making a profit off of the tell-all.

"Of course, it would be nice to have a nice little cushion from selling a book, sure," he said.