My previous post on the same topic, I discussed how matrilineal traditions consider semen as mere nurture but not the essence of life. This is in contrast to patrilineal traditions which consider semen as the essence of life and woman or womb as mere nurture.
One of the examples given was matrilineal Musuo community of China. This community assigned semen the role of rain. I believe matrilineal traditions were strong in northern Indian and Nepali regions close to Sino-Tibetan influence.
During the times of drought it is/was a tradition in Nepala and Uttara Pradesha for women to plough naked in fields to please rain god Indra. We fairly guess how wily wise men of the past synthesized matrilineal traditions with their patriarchal gods. This also gives good clue why Indra upstaged original rain god Varuna.
Seeing thro' patrilineal eyes, matrilineal traditions may look rather strange. This may lead to patrilineal rationalization of those traditions. It doesn't go well with Varuna's character to be enticed by women. But Indra is known for his loose morals.