Young Henry of England, Queen Eleanor’s son, Went to the King when the dancing was done, Said “Father, I’ve found me a maiden to love As fair as the dawn and as soft as a dove, Marie de Provence I must have for my bride” And this, I am told, is what Henry replied. “Marie de Provence, she is slender and tall, And so was her mother, as well I recall, The husband was dark but the daughter is fair, Rather like you if you judge by her hair, My daughter shall never be wed to her brother, Now as you’re my son, not a word to your mother.” A month or three passing, too many to grieve, For the loss of one maiden, again he sought leave, This time he would wed with a wealthy lord’s heir, Perfect of face and with raven dark hair, “The loveliest maiden in all of the lands And Ingibiorg’s holdings fit well with your plans.” King Henry replied, after glancing around, “Another as lovely will have to be found. A husband gets weary the weeks he is banned From the bed of his wife by the midwife’s command. She’s younger than you by some eight months or nine And will be no bride for a child of mine.” “Ellen the Fair is the choice of my heart And surely once wedded we never shall part; The third chance is lucky, or so I am told, She is older than me and her hair is not gold, I will speak to my father, her hand I will win For I’m certain this maiden can not be my kin.” “She is older than you by some two years or three. I remember a time I was single and free And you must not suppose that my youngest romance Was persuading a queen to take England for France. I am sorry my son, but alas it is true That Ellen’s another who isn’t for you.” “Of all the treasures of the world, a wife is what I crave, What is the use of being young and handsome, rich and brave, What profits me to woo and win the fairest neath the sun Only to learn my father has fathered every one? How I can ever find a bride I surely do not know Now I will to my mother to tell her of my woe.” “My son, have not I taught you to forgive and to forget, For all King Henry’s boasting, you have no need to fret, It’s true your hair is like the king’s, as all the world can see, And for the rest, he may suppose you got it all from me, Marry Marie, or Ingibiorg, or Ellen if you please; I cannot vouch for many more, but you’re safe with one of these.
The plot is stolen, the history not entirely accurate; Henry was actually betrothed to Margaret of France at five and married to her at seventeen. But it's at least as accurate as Queen Eleanor's Confession.
See https://en.wikipedia.org/wiki/Shame_and_Scandal_in_the_Family. I remember some version of that song from the 1960s.
There's a filk song — can't remember its title or find it right now — with a similar concept. The daughter of a starship captain considers various candidates for marriage, some of them very alien-looking, and the captain tells her in each case he's the suitor's father. Finally her mother discloses that the captain actually isn't her father, so she can marry whom she wants.