 Well, it's very much frowned upon. Things are changing. You hit the nail on the head when you said that there is an ethno-cultural element to Zoroastrianism. The Zoroastrian community, both in Iran and in India, have been largely endogamous. They've been marrying within the religion. Community elders often talk about marrying within the community and offer a platform for young people to meet. However, the rate of intermarriage is steadily increasing.