Hi Lauraine:
My goodness, you're right, personality provides such an important contribution to effective instruction. Delivery is almost as important as the content being presented. Students are always going to be more receptive to likable instructors they perceive as approachable and willing to help them with their studies.
The good thing is this can be a learned behavior that nearly anyone improve and implemment if they are willing to be better teachers.
Regards, Barry