One of the more notable royals with questionable parentage was King Alfonso XII of Spain. Alfonso was born in Madrid as the eldest son of Queen Isabella II. Officially, his father was her husband, Infante Francisco de Bourbon, Duke of Cadiz. The Duke of Cadiz was given the title of King Consort, one of the few in history, upon his marriage to his double first cousin, Queen Isabella II of Spain, on October 10, 1846. There is evidence that Isabella desired to marry the Duke of Cadiz’ younger brother, Infante Enrique de Bourbon, Duke of Seville. Shortly after their wedding night Queen Isabella II bitterly complained about her husband’s effeminate habits and mannerisms.
These facts had lead to considerable speculation that some or all of Isabella’s children were not fathered by Francisco; this speculation has been bolstered by rumors that Francisco was either homosexual or physically unable to complete the sex act. With Alfonso XII’s biological paternity uncertain, there has been speculation that his biological father may have been Enrique Puigmoltó y Mayans (a captain of the guard). This rumor was put forth by the Carlists as part of their propaganda against the queen.
Let provide some background on Carlism. In 1701 the French Bourbon prince, Philippe, Duc d’Anjou, grandson of France’s king, Louis XIV, inherited the Spanish throne. What the new King Felipe V brought with him to Spain was the ancient Salic Law which barred woman from inheriting the throne as well as passing along succession rights. This law was foreign to the Spaniards because there had been many queen regnants in Spain prior to the accession of the House of Bourbon. This law was not tested in Spain because between the reigns of Felipe V and Fernando VII each monarch successfully produced a male heir.
King Fernando VII, despite multiple marriages, had not fathered a male heir and this lead to a succession crisis in 1833 with the Salic Law being rescinded in Spain. In 1827 King Fernando VII’s third wife, Maria Josepha Amalia of Saxony, died. This forced the aging king into a hasty fourth marriage in order to father a male heir. His bride was Maria Christina of Bourbon-Two Sicilies. The awkwardness of this union was that not only were they cousins multiple times over, King Fernando VII was also her uncle by both birth and marriage. Maria Christina’s mother, Infanta Maria Isabella of Spain, was King Fernando VII’s sister; both were born to King Carlos IV of Spain and his wife, Maria Luisa of Bourbon-Parma. Fernando VII did, however, have two daughters, with Infanta Isabella being the eldest and Infanta Luisa Fernanda being the youngest.
When Fernando VII lay dying his queen had him set aside the Salic Law, which thus made their young daughter succeed him as Queen Isabella II upon his death. Under the old Salic Law the late King Fernando VII’s brother, Don Carlos, Duke of Molina, was heir to the throne instead of any female. Don Carlos revolted and proclaimed he was the legitimate and rightful king and styled himself King Carlos V of Spain. Needing support, Queen Maria Christina (acting as Regent for her daughter) turned to the liberals. She issued a decree of amnesty on October 23, 1833. Liberals, who had been in exile, returned and dominated Spanish politics for decades. The liberals threw their support behind Isabella II and the Carlist Wars resulted. It was in this context that the rumors began flooding in years later that the future Alfonso XII was not fathered by Francisco, Duke of Cadiz, the legitimate husband of Queen Isabella II.
After a tumultuous reign, Isabella II and her husband went into exile with his wife in France in 1868 and adopted the incognito title of Count of Moratalla. In 1870 Francisco and Isabella were amicably separated but in time they actually became good friends. This friendship, which they had certainly not been while she was Queen regnant, was new. The 1874 restoration placed his son Alfonso XII on the throne.
So was Alfonso XII really fathered by Francisco, Duke of Cadiz, or was he really fathered by Enrique Puigmoltó y Mayans, or was this merely a rumor spread by Carlist enemies? From what I understand after reading about this issue from many historians is that the evidence does seem to point to the Duke of Cadiz being a homosexual and although that doesn’t rule out the possibility he could be the father of Alfonso XII, but given the fact that the promiscuity of Isabella II is also well documented, it is reasonable to doubt that Alfonso XII was really fathered by Francisco, Duke of Cadiz.