Here's a lecture that presents two fascinating tales of disease and blood in the royal families of Britain. The first involves the madness of King George III, which present-day forensic historians attribute to variegate porphyria. This condition is also the subject of a famous story of founder effect in genetics, because of its current high frequency in the South African Afrikaner population. Then, the lecture turns to Rasputin and the hemophilia of Tsarevitch Alexei, inherited from Queen Victoria. The influence of genetics on history is reinforced by the recurrence of this genetic disorder in the pedigree of the Spanish royal family as well, all stemming from the one woman at the center of the European royal genealogy.
In the course of the lecture, I cover the concepts of how damage to genes due to random mutations can cause Mendelian disorders, how we can identify the causes of disorders using pedigree information, how forensic investigators can build up a case for medical diagnosis of historical figures, and how gene frequencies can change a lot due to random chance in founder populations.