Persephone was the only one who could move freely both above among the others and in the underworld below among the shadows.

All legends and mythological stories must be understood metaphorically and in symbols. Only then does it start to make sense and start to "logically" fit together.
Woman is through whom the families can be purified.
The man carries on the continuation of his lineage/ancestral blood line (character, abilities, direction,...), the pure woman purifies, the impure woman leads the bloodline to destruction.

I understand that this is very strong coffee for most of those who will read these lines. I won't discuss it any further.