Charles Murray is the co-author of the infamous Bell Curve that aroused a lot of controversy because of its implications that genetics largely explained social and racial inequalities. He has a new book out that focuses on the divisions amongst white people only.
Stephen Colbert interviewed him and, I think, made him somewhat uncomfortable by bringing up is past associations with race issues.
(This clip appeared on March 27, 2012. To get suggestions on how to view clips of The Daily Show and The Colbert Report outside the US, please see this earlier post.)