adywan said:

The Midichlorian idea was dropped long before the final draft of Ep4. You can clearly see from this that they had nothing to do with if you could become a Jedi or not. He was still following the plan of "anyone" could learn to use the force. The force in the OT was spiritual and not a medical condition. He only reintroduced Midichlorians as a measuring device to determine how powerful Anakin was in Ep1.

There are bits in there that made their way into the final version of the prequels.

The rot set in with ROTJ.

Luke and Leia are seen as strong in the Force due to inherited traits which suggests something biological rather than mystical.

If the Prequels had Luke and Leia born in a mystical place or situation, that would explain why they are particularly strong without suggesting weird biology.

**Baronlando got in there before me**