I think this is worthy of 1066 and All That.
I had a postcard of The King of Spain, Alfonso XIII, on a train and wanted to find out how old he would have been at the time (14 or 15). Looking him up on Wikipedia I was scrolling down and noticed a list of ‘Enfants naturels’, in English ’Illigitimate issue'. One of which was born after his relationship with the English Nanny sent over from England by none other than his mother-in-law, Princess Beatrice, daughter of Queen Victoria. (The English Wikipedia page doesn't tell you all of that!)
Note to mother- in- laws everywhere – careful how you help your married daughters.