1066 AND ALL THAT, the comic history of England published in 1930, includes splendidly eccentric exam questions for each historical period; one of the medieval ones is ‘What have you done with your mother? (If Nun, write None)’. In the Arthurian legend, the only significant character who is sometimes said to be the offspring of a nun (or a virginal and virtuous princess) is not a king or a warrior hero but Merlin the magician. He is fathered clandestinely by a mysterious visitor, in some versions an incubus, but saved for the side of good by the holiness of his mother; in some she remains a virgin, suggesting a surprising parallel between Merlin and Christ. There is already a link between them in that their birth stories demonstrate Otto Rank's theory that in mythology and legend extra-marital and clandestine encounters often produce great heroes (this is also true of Arthur himself, conceived in an extra-marital tryst through Merlin's magic). These clandestine births often result in accusations against the mother, in both classical and medieval narratives. In Robert de Boron's Merlin, an influential French verse romance written around 1200, the precocious boy successfully defends his mother against a charge of fornication; and Arthur's mother too is falsely accused before the truth about his parentage is revealed (discussed in more detail below). No doubt this reflects historical anxieties about the chastity of queens and aristocratic ladies.

Much has been written about the importance of fathers, and father-son relations, in Arthurian literature; fathers may be absent, but their names convey both noble status and expectations – of inheritance, or a duty to avenge a death, for instance. The popular Fair Unknown motif is frequently used about promising young knights who often turn out to be fathered by Gawain, but little is said about their mothers. How much do parent and child interact, and how do they feel about each other? Some Arthurian knights are deeply moved by discovering the identity of their mothers or by being reunited with them. Some are reproached for not being more devoted to their mothers. Some defend their mothers, but others blame and punish them for inappropriate behaviour. In a range of medieval Arthurian texts, and also some modern ones, the mother-son relationship can be of profound significance.