The Classical Roman idea of a “genius” couldn’t be more different from the modern one. To them the genius was:
the superior or divine nature which is innate in everything, the spiritual part, spirit; hence, the tutelar deity or genius of a person, place, etc. (cf.: lares, penates). (Latin Dictionary)
There are two different theories as to the meaning of the word. First, that it comes from the Roman word gens, “tribe, people” from an Indo-European root word. Second, that it means “begetter”, and signifies a fertility spirit. More broadly, a genius could be the spirit of a person or place, as in the expression genius loci.
Women seem to have had their own form of genius, called a juno. (This is a contested idea: the Wikipedia article on Juno denies it completely, while the Brittanica site and the Dictionary of Roman Religion are for it.) However, enough scholars seem to accept the idea that I’m willing to see it as valid. I’m sure even in a society as patriarchal as ancient Rome women took pride in their children and their lineage, and those feelings found their own religious expression.
Junos and Matrons
The Germanic goddesses known as the Matrones, spirits of protection and fertility, seem to have been a great deal like the juno. (Like the genius concept, matrons came in all kinds, from suis matribus, my mothers, to the mothers of an entire province.)
In Northern Italy and Germany we find inscriptions mentioning the Iunones, or junos, which implies a cult of mother or protective goddesses was strong there. From Northern Italy we have 59 inscriptions to the Matrones, 32 to the Iunones, and four for both. At Rövenich in Germany, the Iunones were associated with the local Gabiae cult, the “giving goddesses”. Two of the 10 votive stones found there mention the junos.
The first substitutes the word for matronis, changing their title from the Giving Mothers to the Giving Junos, Iunonibus Cabiabus (C.I.L. XIII: 8192), while the second is dedicated to the Iunonibus sive Gabiabus, to the Junos or the Gabiae (C.I.L. XIII: 8612). Two different people commisioned the stones, so there may have been a local cult of the junos, or at least sufficient awareness of Roman religion to make the comparison. (Simek: 97 and French: 77)
In Gallia Belgica, we find the Sulveiae and Iunones pairing up in the same way, as the following inscription shows:
Sulevis Iuno/nibus sacr(um) / L(ucius) Cas(sius) Nigri/n[ianus(?) pro] / se
CIL XIII, 3561 Rinxent (Département Pas-de-Calais, Gallia Belgica)
Clearly, the Iunones were a subset of the larger matres/matronae cult, and could be paired with other protective and giving goddesses.
Gefjun and Idunn
The Norse equivalent of these mother-cults was probably the cult of the disir, who seem to have embodied the spirit of a family, protecting and guiding them. But it’s not hard to think of individual goddesses whose cults seem to have grown from those of the Matronae. Rosmerta is an obvious example. Two Norse goddesses, Gefjun and Idunn, also fit this profile, albeit in very different ways.
Gefjun’s name connects her to the Gabiae, giving goddesses. Some see her as an aspect of Freyja, but she does have her own myths, including one in which she tricks the king of Sweden into giving her land.
She could be said to use her power of procreation in a very Odin-like way. After she seduces the king and gets his promise of land, she becomes pregnant by a giant, and gives birth to four sons, whom she disguises as oxen. When they plow out the land for her, they dig so deep that they break off from Sweden altogether, forming the island of Zeeland. Gefjun successfully harnesses the excessive sexuality of the giants to her own ends.
This myth seems to contradict all the other lore about Gefjun, which states that she is a virgin goddess, and that unmarried women go to her at death. The odd incident in Volsa thattr involving some sort of ceremony with a preserved horse’s penis seems to back this up. The penis is passed from hand to hand, with each person improvising a verse as they take it. When it comes to the daughter of the house, she says:
I swear by Gefjun
and the other gods
that against my will
do I touch this red proboscis.
accept this holy object,
but now, slave of my parents,
grab hold of Völsi.
(trans. Eybjorn, quoted in Wikipedia entry)
Although I suppose a goddess who protects virgins but has a somewhat equivocal reputation might be the right one to mention in this context.
The mother-goddesses often appeared in groups of three, and usually one of the three would be a young woman, with hair unbound, while the other two wore the headdresses of married women. French suggests that Gefjun may be the third goddess. (French:77) A “virgin” goddess would have been an odd inclusion among a group of goddesses of married women, but perhaps she represents a potential wife.
Idunn, on the other hand, is a married woman and thus a natural fit with the matronae. Many modern writers, especially John Lindow and Margaret Clunies-Ross, have seen her apples of immortality as symbolic of the power of procreation, which guarantees immortality for the family line. Which ties her very neatly to the junos in particular.
Her power is only exercised within the bounds of her own kin. She is married to another Aesir god, the poet Bragi. Her only myth emphasizes how valuable her power is, when the giants kidnap her and the Norse gods have to face up to mortality. They rescue her, and kill the giant who took her and her apples. Usurpers will be punished; a similar Graeco-Roman myth about Juno/Hera ends with the would-be seducer Ixion bound to a wheel in the underworld.
Oddly, Idunn doesn’t have any children of her own. Perhaps her power is concentrated in the apples. In fact, since her story seems to come before the whole tragedy of Baldr, you could argue that the suddenly aging gods began to think about succession for the first time when she vanished, whereas up until then they hadn’t needed to think about inheritance or the next generation.
Gefjun provides for the next generation: her new island was Zeeland, which she gives to the first king of the Danes, Skjold. Both goddesses are defined by their gifts: whether immortality or territory. Both represent the power of sexuality to benefit the family, although Gefjun goes about it in an unorthodox way.
Adkins, Lesley and Roy A. Adkins 2000: Dictionary of Roman Religion, OUP. (entry on genius)
Clunies Ross, Margaret, 1994: Prolonged Echoes: Old Norse myths in medieval Northern society, vol. 1, The Viking Society Vol. 7, Odense UP.
de Grummond, Nancy Thompson 2006: Etruscan Myth, Sacred History and Legend, University of Pennsylvania Archaeology. (Google Books)
French, Kevin 2014: “We need to talk about Gefjun: Toward a new etymology of an Old Icelandic theonym.”, diss. (pdf available here)
Green, Miranda 1997: Dictonary of Celtic Myth and Legend, Thames and Hudson.
Lindow, John, 2001: Norse Mythology: A Guide to the Gods, Heroes, Rituals and Beliefs, OUP, New York and Oxford.
Simek, Rudolf (trans. Angela Hall), 1996, Dictionary of Northern Mythology, D. S. Brewer, Cambridge (entries on Gabiae, Matron cult).
Article on Celtic Goddesses, includes matres, in Celtic Review
University of Pennsylvania Dictionary of Greek and Roman Mythology (Genius)
Lady of the Labyrinth on Matronae names (scroll right to the bottom for some possible Eddic mentions of the mothers)