The Orléans are almost incestuous:
The present Count of Paris is a descendant fro 5 of Louis Philippe's sons.
Two brothers Fernand d'Orléans and François de Joinville had two first cousins who got married, Robert de Chartres and Françoise de Joiville.
Their son was Jean, duke of Orléans who married a second cousin, daughter of 1st cousins:
The same Fernand d'Orléans and, this time, his brother Antoine de Montpensier, had Louis-Philippe, count of Paris and Isabelle d'Orléans Montpensier. They had a daughter, Isabelle who married her cousin Jean.
Jean's son, Henri, count of Paris, married her cousin Isabel d'Orléans-Bragança, daughter of Pedro O-B, grand-daughter of Gaston count of Eu, and great grand-daughter of Louis duke of Nemours, the brother of Fernand, François and Antoine.
Finally, their sister Marie married Alexandre of Wurttemberg, mother of Philipp, grand-mother of Albrecht, great-grand-mother of Philipp and gr-gr-gr-mother of Marie Therese who married Henri and Isabelle OB's son, the recently deceased Henri count of Paris.
Other 1st cousins marriages between the Orléans:
Sisters Hélène and Isabelle married Emmanuelle-Filiberto d'Aosta and Jean duke of Orléans.
Their children Amedeo and Anne got married.
The present duke of Aosta and his 1st wife Claude d'Orléans are 2nd cousins.
Queen Isabel II of Spain and her husband, King-Consort Francisco were first cousins and cousins several times over.
Their fathers were brothers
Their mothers were sisters
Their maternal grandparents were first cousins
Their maternal grandmother was a sister of their fathers
Their maternal grandfather was a first cousin of their fathers.
Everybody knows that there are four ways in which such unions are possible, and there have been plenty of occurrences of all types, throughout European royal history --
1) The father are brothers (e.g. Prince Ludwig and Princess Irmengard of Bavaria, in 1950; to the best of my knowledge, this was the last time such a thing happened)
2) The mothers are sisters (e.g. The Grand Duchess Charlotte of Luxembourg and her consort, Prince Felix of Bourbon-Parma, in 1919; again, I believe this was the last occurrence of such a union)
3) His father and her mother are brother and sister (e.g. Grand Duke Kirill Vladimiovich of Russia and Princess Victoria Melita of Edinburgh, in 1905; I'm not sure if this was the last such example)
4) Her father and his mother are brother and sister (e.g. Grand Duke Ernst of Hesse-Darmstadt and the same Princess Victoria Melita of Edinburgh, in 1894; again, I'm not sure if this was the last such example)
Anyhow, I was just wondering if anybody knew which type of first cousin marriage has been the most common, in European royal history. Surely somebody would have statistical data on the matter.
Also, are my examples correct, about the last time a particular type of cousin marriage occurred? Like I said, I'm a little murky about the latter two scenarios; even with the first two, there could be more recent examples.