The birth of twins in the literary art of the Middle Ages frequently marks an opportunity for one woman to accuse another of adultery and thus the twins as illegitimate. Erik Kooper has analysed twenty European stories, many of which were translated, redacted and adapted, and he divided these according to the way in which twinship is represented. ‘If one thing becomes clear from this kind of classification,’ Kooper concludes, ‘is that multiple births do indeed lead to numerous kinds of disaster, both for the mother and for the children.’ Of the twenty or so stories he lists, only four of these leave mother or child protagonists untainted by accusations of adultery or monstrous birth. In stories that are free of these kinds of accusation, like the late twelfth-century French story Aiol whose royal twins are born in a prison and later exposed, twins are by no means free of other kinds of peril. Similarly, in the early fifteenth-century romance, Sir Torrent of Portyngale, the eponymous hero is separated from his twin sons without negative judgement being attached to the phenomenon of twinning, but that does not mean that its twin protagonists are straightforwardly celebrated either. The stories benefit from the narrative pathos and closure forged through the eventual reunion of parents children: extending and complicating the romance drama of ‘setting out’; incorporating, in both senses, multiple protagonists. These twin stories, however, form a minority. Many others involve an accusation of adultery and/or animal birth, the threat of such accusations, and the retribution served by the religious and civic orders that these accusations threaten to disrupt.
One of the most famous narratives in which the mother of twins is accused of adultery is found in Marie de France’s short romance, Lai Le Fresne. It is one of Marie’s shortest lays, written in French some time in the late twelfth century, and it bears close similarities to ballads such as ‘The Man With Two Wives’ and ‘Fair Annie.’ Marie’s story begins with the birth of twin sons to one noble woman. A jealous neighbour claims that the twins are not the sons of her husband but that the noble woman has, in fact, had sex with two men:
Ich have wonder, thou messanger,
Who was thi lordes conseiler
To teche him about to send
And telle schame in ich an ende,
That his wiif hath to childer ybore.
Wele may ich man wite therfore
That tuay men hir han hadde in bour;
That is hir bothe deshonour. (65–72).
The poem matches contemporary theses advanced by natural philosophers and theologians, such as Albert the Great, who argued that superfecundation, female sexual proclivity, and the generation of twins were all entwined. Note that in Marie’s story the twins are treated as the sole evidence of an adulterous act: it is not supplemented by any other kind of visual, verbal or written proof. Shortly after making this accusation the nameless woman who accuses her neighbour then conceives twin daughters of her own; she is therefore incriminated by her earlier accusation. Not only does this disrupt the moral polarity between accused and accuser, it also contravenes the major conventions of romantic literatures, epitomised by figures such as Guenevere and Iseut, which tended to amplify acts of adultery with threats of infertility. In a complex way, the issue of twins as a result of an adulterous union compromises the gendered, political, religious, and literary conventions of the period; its narrative impact is to suspend a damaging doubt over who is the rightful father and legitimate heir.
Multiple birth – a taboo that inspires accusation, punishment, and abandonment – also seems to displace the incest taboo that frequently motivates infant exposure in stories about male foundlings. Hence, the accusing noble woman in Marie’s lai, now pregnant with her own twins, seeks to protect herself and the reputation of her offspring. First she considers killing one of her daughters – a reflection of how exposure was a response to unwanted births during this period – but then gives one infant child to a servant who takes and hangs it in an ash tree, wrapped in an expensive cloth and with her mother’s ring. She leaves the child in the grounds of a convent and it is by this ash tree, le frêne in Old French and frein in Middle English. Named after the tree in which she was found, Frein is raised and educated by the abbess’ niece and later falls in love with a wealthy knight called Guroun. But the knight is persuaded to marry someone rich and have legitimate children. Without realising the family connection the knight decides to marry Frein’s twin sister. Frein, though sorry for her loss, graciously adorns the matrimonial bed with the cloth in which she was abandoned and, when this garment is recognised by her mother, she also produces the ring and explains how they came into her possession. Her sister’s marriage is quickly annulled and Frein marries Guroun. Frein’s twin is married to a suitably wealthy knight and, despite the years that have passed, order is restored.
To the turbulent plot of Frein we can add Octavian, a popular family romance throughout the fourteenth century, initially composed in Old French and then abbreviated into two Middle English versions. In this story, the Emperor Octavian and his Empress seek an heir – there are concerns that the Empress may be infertile – and so they build an abbey in the hope that their piety may bring them divine favour. Their prayers are answered in the shape of twin sons. In this respect, their children have divine connotations; a sign of divine intervention and a resolution to anxieties surrounding royal succession: ‘An abbaye than he gerte wyrke so / And sone he gatt knave chidire two, / Als it was Goddis will’ (82–84), In a way which corroborates the notion that twin births are difficult and painful, the text stresses the physical exertion and exhaustion of twin delivery: ‘Full grete scho wexe with paynnes sore’ (86). Further difficulties arise when the Empress’ mother-in-law claims that the twins fathered by the cook’s assistant and the Emperor exiles wife and children. The family undergo further separation when each twin is abducted, the first by an ape and the second by a lioness. After further abductions, adoptions, giant killings, battles and romantic conquests, displays of taste and indications of their innate nobility, the adult children are restored to their parents. At the point of reunion, ‘full joye there was also / At the metyng of the brethir two’ (1898–1899). In a fashion that seems to stress the dramatic capacity of twinning rather than any intrinsic or absolute quality unique to twins, their ‘true’ identity is revealed by their actions; through their valour at court and on the battlefield. The deceitful mother-in-law, now threatened by her husband to death by fire, takes her own life. According to literary convention, order and peace are restored.
As much as it is important to stress a continuity between works of natural philosophy, medicine, and literature in the Middle Ages, which all in their different ways highlight how twinship was viewed as a fundamentally disruptive event – a woman’s natural and spiritual burden – it is also essential to identify the drama and entertainment afforded by the birth of twins; twins are catalysts for demarcating the orderly from the disorderly, the usual and the unusual, the desired and the undesirable. This optical and instrumental quality of twinning is not specific to this period of human history. Though what is viewed, calibrated, or measured may change, the inclusion of twins as evidence for the orders and aberrations of nature is a persistent aspect of human self-assessment. The category of ‘twin’ is unusual, therefore, since it is not simply defined by authorities who build upon one another’s knowledge in an accumulative fashion, but twins gain their transhistorical meaning from the many different and divergent kinds of authority that is achieved using their bodies.
 See Erik Kooper, ‘Multiple Births and Multiple Disaster: Twins in Medieval Literature,’ in Conjunctures: Medieval Studies in Honor of Douglas Kelly
- Douglas Kelly, Keith Busby and Norris J. Lacy (Amsterdam: Rodolpi, 1994), pp. 256–260.
 Kooper, ‘Multiple Births and Multiple Disaster,’ p. 260.
 The extent to which Marie de France’s Lai le Freine is a ‘romance’ in a generic and critical sense is discussed by Elizabeth Archibald, see ‘Lai le Freine: The Female Foundling and the Problem of Romance Genre,’ in The Spirit of Medieval English Popular Romance, edited by Ad Putter and Jane Gilbert (Harlow: Longman, 2000), pp. 39–55.
 See Francis J. Child, The English and Scottish Popular Ballads, vol.2 (Boston: Houghton, Mifflin and Co. 1883-86), II.63–83, and Erik Kooper, ‘Multiple Births and Multiple Disaster: Twins in Medieval Literature,’ pp. 253–270.
 All quotes from Marie de France, Lay le Freine, in The Middle English Breton Lays, Edited by Anne Laskaya and Eve Salisbury (Kalamazoo, MI: Medieval Institute Publications, 1995), pp. 65–74.
 See Peggy McCraken, ‘The Body Politic and the Queen’s Adulterous Body in French Romance,’ in Feminist Approaches to the Body in Medieval Literature, edited by Linda Lomperis and Sarah Stanbury (Philadelphia, PA: Pennsylvania University Press, 1993), pp. 29–64.
 See Elizabeth Archibald, Incest and the Medieval Imagination (Oxford: Oxford University Press, 2001).
 John Boswell details the history of child abandonment in the Middle Ages; he writes that ‘between 1195 and 1295 at least thirteen different councils in England alone passed legislation directly or indirectly bearing on the abandonment of children’, see The Kindness of Strangers (New York: Vintage, 1990), p. 322.
 On medieval theories of resemblance, see Paul Vincent Rockwell ‘Twin Mysteries: Ceci n’est pas un Fresne,’ in Conjunctures: Medieval Studies in Honor of Douglas Kelly, pp. 487–504.
 See Harriet Hudson, ‘Octavian: Introduction,’ in Four Middle English Romances: Sir Isumbras, Octavian, Sir Eglamour of Artois, Sir Tyramour, edited by Harriet Hudson (Kalamazoo, MI: The Consortium for the Teaching of Middle Ages, 1996), pp. 45–52.
 Citations are to Harriet Hudson’s edition of the Northern, Thornton version, Four Middle English Romances, pp. 53–114. Line numbers are given in parentheses in the main body of the text.