No doubt that it could be "culturally ingrained", but I suspect that there is an in-built element. We evolved from and are still animals, and nearly all human morality can find its origins in instinctual disgust reactions of one kind or another.
In our washed, shaved, antiperspirant'd, deodorized then cologne'd world we've lost touch with our animal senses.
Even if it were fully in-built it doesn't mean that it wouldn't be accepted or tolerated, but might be treated, culturally, as an exception - eg as a third sex or parallel community. Even in ancient Greece it was fine for men as pederasty, but not really for adult partnership with our "equal marriage" concept.
Ancient peoples must have had pretty much the same discussions that we do, just with less known facts to hand.