The question is how to do it, because there are many possible paths, some short and some long, some more interesting and some less interesting.
I suppose the shortest and least problematic path is something like:
vagina, vulva → source, point of origin, birthplace → 3S pronoun → complementizer → predictive/counterfactual marker
Perhaps with an extra stage or two between "point of origin" and full-on grammaticalization as a pronoun. Like going from "source" to "source of debate/discussion, source of an issue" to "the one in question".
The question is how to do it, because there are many possible paths, some short and some long, some more interesting and some less interesting.
I suppose the shortest and least problematic path is something like:
vagina, vulva → source, point of origin, birthplace → 3S pronoun → complementizer → predictive/counterfactual marker
Perhaps with an extra stage or two between "point of origin" and full-on grammaticalization as a pronoun. Like going from "source" to "source of debate/discussion, source of an issue" to "the one in question".