For this specific notion - I can't remember honestly. But most of the book is backed up by sources / studies. As I noted in this thread - I don't think 100% of

For this specific notion - I can't remember honestly. But most of the book is backed up by sources / studies. As I noted in this thread - I don't think 100% of what author communicates in the book is factual or conclusive, but he does a great job of collecting multiple perspectives and studies to combine it into one thought provoking read. Like any book that has an agenda/angle, a healthy dose of skepticism is always required.