The lecture at Gresham College by Steve Jones, Emeritus Professor of Genetics at University College London, on Incest and Folk-Dancing: Two things to be avoided, is now available as a video at http://www.gresham.ac.uk/lectures-and-events/incest-and-folk-dancing-two-things-to-be-avoided.
From the lecture overview:
Professor Jones discusses patterns of relatedness in ancient and modern populations and how they can be measured from the records, from surnames, and - more and more - from the DNA. The pedigree hidden in every genome reveals some quite unexpected patterns of kinship and suggests that some may be very relevant to the chances of disease. However, the evidence that close kinship is breaking down is, in this modern and mobile world, very persuasive and it may be that the most important event in human evolution, and even in human health, was the invention of the bicycle.Worth watching if your perspective on genealogy takes you beyond the world of the genealogical proof standard.