[Obi-Wan can see and hear the surprise, or was it horror, in reaction to what he was telling the shade. It didn’t really surprise him. Most wouldn’t know such a life and not understand it.]

No it’s not genetic, not really. It can be, but often it just shows up randomly.

With the Order gone, there will be no balance in the Force. Those born with sensitivity will either never know it, be unable to control it, or they will be used for evil by the Sith now ruling the galaxy. That is if they are simply not killed. Either way it is a tragic outcome.