Hi, AKS. You wouldn't happen to know anything about that poem I quoted in my OP, would you? Including what its translation is in English? I've been told by a Finnish online friend and some Finnish online acquaintances that that particular poem is written in the equivalent of Middle English. And am I right in thinking that those poems about Kullervo come from all over the Finland/Russia border, both Ingria and south Karelia?

BTW, you might know that this story was also Tolkien's favourite Finnish folktale. He did a retelling of it in 1914 but never finished it, which you can find here: The Story of Honto Taltewenlen (Kullervo, son of Kalervo) by J.R.R. Tolkien, with notes by Verlyn Flieger. In that version, the incest is the result of a curse by the evil mistress.

The story was the basis of Tolkien's later Narn I Hin Hurin, The Children of Hurin, which also has a young hero, Turin, whose name is similar to one of the names of the incestuous brother in some of the Ingrian songs separated from his family as a child, living in a foster home, where he is taunted by a member of the household, who he later kills. He then falls in love with his unknown sister, then kills himself with his talking sword, asking it to drink his blood, when he learns who she is.

In The Children of Hurin, Turin and Nienor, his sister, actually get married and Nienor gets pregnant. Glaurung, the Dark Lord Morgoth's greatest dragon, who cursed her with amnesia, tells her, after listing all of Turin's bad qualities and deeds when he meets her, "But the worst of all his deeds you shall feel in yourself." Then she leaps off a cliff into the sea in despair and drowns herself- the same as the way Kullervo's sister dies. Soon after, Turin asks his sword Anglachel, which can talk, glows and loves to taste blood, to kill him, and falls upon it.