This is all self-reported, and people who don't have emotions don't reach out to support groups or express their feelings about not having feelings on message boards.

Also, there has never been a thing called an emotion detected in or on the body of a human. I think the leading theory is that 'emotion' is a rationalization of the current state of one's sympathetic and parasympathetic nervous system. It's a self-application of theory theory.

https://en.wikipedia.org/wiki/Theory-theory