Genesis 6 talks about Nephilim sons of God who were giant and Sitchin had his own personal understanding of the meaning (not shared by scholars and he was not one of them but studied economics). The word Rephaim is also relevant. These giants mentioned in all cultures (and though there are hoaxes, there still are some examples of the giant bones and weapons used in the past). The text suggest (you'll have to search about the people who say the sons of god were angels and others who talk about Sethian people, etc) these giant were not merely humans but people who became famous like semi-gods because they were offspring of male gods and woman from earth. Legends are explicit about their height, size of their eyeballs and head, the use of long hair like women, the homosexuality, fire wiping them out, etc, etc, etc. Interesting the bones of the legs of some of them fit exactly with the description (for example in Inca "myths").

The question is, how would women begot these giant babies which sometimes killed them. The legends sometimes detail the women were ripped off at the very moment of having sex with giant offpsring who ate the equivalent of 50 common men. Suppose the spirit can materialize into human shape, would it be disguised into male flesh or female flesh? Incubus or sucubus? Would they hold the semen of an earthly being into their female human transformation and then change from female into male human shape to insert the semen in women from earth this time?

Why would the legends prefer the idea of male gods who implanted their seed into earthly women? The fact the myths are "universal" in that sense is impressive.