Hi Kim! It seems likely enough that as we progress through physical incarnations, we carry with us (in some measure) the previous knowledge gained. This is all rather speculative, but the "old soul" theory seems to have some merit. In addition to this, I believe conscience grants all access to morality, though for it to speak to us clearly, the mind must be in close alignment with Truth, or made to move aside so we can hear clearly.
To your first point, that phenomenon demonstrates well how cultural conceptions of morality cannot be in alignment with Truth, for moral Truth is eternal and unvarying across time and place.
Yes, eternal truth's and not moral's based on convenience or to be aligned with what is degraded through societal norms which often enough are attached to someone making money off from that debasement.
Thinking too of the importance of keeping our bodies healthy so that our consciousness can reach us too.