I think I had in mind...
An option in preferences so that all Series genre information (may apply to other information also) is included in the episode genre. Maybe a tick box where you can choose to enforce the episode genre to be the same as the series. And another option where every genre assigned to the series is replicated in the episode, but they don't have to be identical, thus for highly variable series such as Nova, you can have variability for each episode.
Thanks
Craig