I don't know for sure, but I don't think it's passed down. I think it's just a matter of luck and then exposure. It seems like humans who have had continued and prolonged contact with seraphim are more likely to develop resonance than people who don't.
Unfortunately a lot of our historical records are pretty spotty. The general consensus says that humans lost their reverence for seraphim and took their blessings for granted. As a result seraphim had to leave human towns and cities and withdrew back to nature. Most seraphim are nomadic and travel around; it's pretty rare in my time for them to settle anywhere for long, and less so near humans.
no subject
Unfortunately a lot of our historical records are pretty spotty. The general consensus says that humans lost their reverence for seraphim and took their blessings for granted. As a result seraphim had to leave human towns and cities and withdrew back to nature. Most seraphim are nomadic and travel around; it's pretty rare in my time for them to settle anywhere for long, and less so near humans.