For day 5 of “30 Days of Deity Devotion“, we’re outlining Frigg’s family tree.
In the Prose Edda, Fjörgynn (personified Earth? maybe?) is said to be Frigg’s father. But the Prose Edda is extremely unreliable on this kind of thing, and the relationship isn’t attested elsewhere.
Otherwise, Frigg’s parents aren’t known.
Frigg might be sisters with Fulla or might be “very close” with Fulla. Because of such an abundance of fostering that eventual sexual partners were sometimes referred to as “brother” or “sister,” it’s really hard to tell what’s happening here. In addition, the attestation of their “sisterhood” comes from a 10th century German manuscript referring to their counterparts Frija and Volla. In heathenry, there are many related counterpart deities that arose as religion and culture changed across time & place, and they’re not always actually the same person.
Frigg is the wife of Odin.
Frigg is Baldr’s mother, and his death is noted repeatedly as her greatest grief. That he is the blood son of Frigg and Odin is without a doubt.
Hermóðr has been referred to as Odin’s son and implied to be Baldr’s brother. But he has also been referred to as Odin’s servant, which makes sense in the context of his few attestations. However, if he is Baldr’s full blood-related brother, that would make him Frigg’s son.
In the Prose Edda, Frigg is said to be the mother of Thor, but, again, the Prose Edda is really unreliable on these things. Elsewhere, it is said that Jörð (a giantess/possibly personified Earth) is his mother. It’s my personal belief that Frigg raised him and Jörð is his birth mother.
Frigg was the foster mother of Agnar Hrauðungson. She fostered him in a bet with Odin over whose foster son would become king.
Odin is also the father of Víðar (by Gríðar) and Váli (by Rindr), and thus they may have also been foster-sons of Frigg. Other possible sons of Odin include Bragi, Meili, Sigi, Skjöldur, and Ítreksjóð.
More distant relations
Nanna is Baldr’s wife and thus is Frigg’s daughter-in-law. Through them, Frigg is also grandmother to Forsetti.
Vili and Ve are Odin’s brothers and thus Frigg’s brothers-in-law. She might have also briefly partnered with one or both of them.
Bestla is the mother of Odin and thus Frigg’s mother-in-law. Borr is the father of Odin and thus Frigg’s father-in-law.
If Frigg is Thor’s mother, then that would make her Sif‘s mother-in-law and grandmother to Þrúður, Magni, Moði, and Ullr.