In Zoroastrian Middle Persian (Pahlavi) texts, the term xwēdōdah (Av.xᵛaētuuadaθa, khevtuk-das) is said to refer to marital unions of father and daughter, mother and son, or brother and sister (next-of-kin or close-kin marriage, nuclear family incest), and to be one of the most pious actions possible. The models for these unions were found in the Zoroastrian cosmogony. Men were allowed to marry their daughters, sisters, and mother. It was “not merely tolerated, but indeed regarded as acts of piety and great merit, and even efficacious against the demonic forces.” The religious leaders of the time promoted marriage within the family, claiming it imitated the creation. Moreover, priests claimed that incestuous marriage “produced stronger males, more virtuous females, and higher quality and quantity of children, and it protected the purity of the race and propagated it.” This was met by much resistance, led to more conversions from Zoroastrians to Christianity, and is thought to have led to the downfall of the Zoroastrian religion. Finally, The number of wives a man had, was reliant on the means of the man. Thus, there wasn’t as much polygamy in the lower classes as in the wealthy class because men could not afford it.
There are two extreme when it comes to the pre-Islamic history of Iran. On on side you have the so called Islamists who paint a picture of pre-Islamic Iran as if it was worth nothing, a dark age with no achievements whatsoever. Then you have the other extreme, represented by Iranian nationalists or in more extreme cases blatant apostates (nine times out of then a former Twelver Shia), Anti-Arab and Anti-Islam bigots who see all evil in Islam and in Arab culture and all good in the Pre-Islamic era of Iran, including the Zoroastrian religion. There is no doubt that Persians were a great people before Islam, however the blessings that Islam brought to Persia are undeniable, at least to the eyes of an open minded, non-biased (and non racist) researcher. The following article does not want in any shape or form suggest that all Persians in Pre-Islamic Persia used to wed their mothers and sisters, this is absurd (and part of Zoroastrianism), same as it is certainly not true that all Arabs used to bury their daughters alive. However, both aforementioned despicable practices were still common to a certain extent and it was Islam that abolished both, the superstition and wickedness of Zoroastrianism and pre-Islamic Persian culture of wedding ones mother and sister and the superstitious and wicked pre-Islamic Arab culture of burying ones daughter alive.
Avesta literature is Zoroastrian literature, it’s the Bible of the Zoroastrians, full of filth, paganism, polytheism, degradation of women and perverted rulings (such as marrying ones mother and sister!). Of course these scandals have never been really analysed and exposed to English speakers, for the Iranian Anti-Islam lobby around the world has been busy trying to find all sorts of faults in Islam, portraying it as the incarnation of evil supposedly Zoroastrianism and Pre-Islamic Persia were a heaven on earth that was destroyed by savage Arabs of the desert of Arabia. Nothing can be further from the truth than that, since it was Islam that has taught the Persians to stop marrying and penetrating their mothers and sister. If it wasn’t for our master Ali Ibn Abi Talib and the Caliph of his time, our master Omar Ibn Al-Khattab (the later was encouraged by the former to fight the Persian Sassanian Empire and spread Islam to Persia) then we Persians wouldn’t have known the difference between our mothers and sisters.
Al-Hamdulillah for Islam.