Sure, but does that amount to pedigree collapse for Elizabeth or Charles, which is what Oliver is insinuating with his “cousins marrying” stuff? Each of them has eight different great-grandparents, for a total of sixteen different great-grandparents in each generation. Once you start going past great-grandparents, it’s more of a historical background than anything that relates to the current genetic diversity in the royal family.
Here’s the passage from the Wikipedia article on Pedigree collapse, talking about examples in European royal families:
Among royalty, the frequent requirement to marry only other royals resulted in a reduced gene pool in which most individuals were the result of extensive pedigree collapse. Alfonso XII of Spain, for example, had only four great-grandparents instead of the usual eight. Furthermore, two of these great-grandparents, Charles IV of Spain and Maria Luisa of Parma, who themselves were first cousins, were parents of another great-grandparent, Maria Isabella of Spain. Essentially, Alfonso’s parents were double first cousins, i.e. his two grandfathers were brothers and his two grandmothers were sisters, meaning there were only two sets of great-grandparents rather than four. In addition, each grandfather had married one of their sister’s daughters, i.e. they had each married their sororal niece.
The most extreme example was Charles II of Spain:
In the case of Charles II, the last Habsburg King of Spain, there were three uncle-niece marriages among the seven unions of his immediate ancestry (i.e. parents, grandparents and great-grandparents). His father and two of his great-grandfathers married their nieces. His paternal grandparents were first cousins once removed, but they comprised two of the seven marriages because they were also parents to his maternal grandmother. His maternal grandparents’ marriage and the final marriage of great-grandparents was between first cousins.
That’s nothing like the marriages and descent in the British Royal family, past or present.
There’s also the point that DrDeth makes, that in small villages in England, there could also be pedigree collapse, prior to the increase of mobility in the 19th century. So saying that the British Royal family has more pedigree collapse than average, runs into that issue: how do you assess that they have a greater history of pedigree collapse prior to the mid-19th century than was common in the English population at that time?
The pedigree of the royal family is more well-documented than John Brown marrying his cousin Mary Smith in Upper Tooting, but to say that the royal family had greater pedigree collapse than average requires a lot more genealogical research than just pointing to Victoria and Albert, the last example of a monarch marrying a first cousin that I can find. That was in 1840. I find it difficult to say that marriage, 184 years ago, meant that Elizabeth II, Charles III, and the current Prince of Wales have greater pedigree collapse than average.
? Mostly I intrinsically disdain royals for for being a parasitic anachronism, so I think mocking them is a public good. Even if slightly hyperbolic mocking 
.
