Well, I would guess there simply has to be an hereditary concept to the Jedi.
After all, Luke and Leia had it, and it seems to have been implied that they gained it from Anakin.
In the EU, all three Solo children have it because Leia was there monther. Also, Corran Horn came from a line of Jedi and they all had the distinction of not being able to master telekinesis.
What I would say is that I don't believe the strength of force ability in the parent has a direct reflection on the strength of force ability of the child.