Well, I'll just ask a simple question. Do you believe the genetic makeup of an individual can influence their type (ie do you think no one is more susceptible to defects or disease than the next due to their dna. If you do I'm sure AMA would be interested in your research)?
Has Butler performed conclusive genetic/dna research pertaining to the subject? He does seem to be a hell of a marketer, but didn't see anything on him as a research scientist. I don't know so I'm asking.
Until then, I'm going to hedge my bets by going on my experience.