Dr. Bullough was a participant in Closer to Truth: 

Show 114, "Does Sex Have a Future?"
Show 209, "Who Needs Sex Therapy?"

Dr. Vern Bullough

Vern Bullough is a medical historian who specializes in the history of sex, sexual practices and taboos, and the diverse groups of "sex workers.". He has been professor at several universities (Buffalo, University of Southern California (USC), Cal State at Northridge) and has written over 50 books, including Sexual Attitudes: Myths & Realities, Human Sexuality: An Encyclopedia, and Frontiers of Sex Research.