JAMSHID, Myth of Jamshid? Encyclopaedia Iranica
According to Zādspram, Zarathustra was descended from Nēryōsang through Pōrušasp and from Frēdōn son of Āspīy through Pōrušasp’s mother Wēzag and from Jam through the Āspīyān family (cf. Bundahišn 35.52, on Frēdōn’s descent). The Bundahišn (35.8) also records that Pōrušasp was descended from Manuščihr, a tradition found later as well (Ṭabari, I/2, pp. 681-82, tr., IV, p. 77; see the genealogical tables in Justi, pp. 390-93). Jam and Jamī (Jamag). In the Rigveda, Yama has a twin sister Yamī, while, in Iran, only Pahlavi Jam has a twin sister Jamī (Jamag).
Was Zarathrushta a 'Puru'?