I have a little theory. Maybe you can help me. It is the following idea.
Given the fact that the first generation of Christians was mostly purely from Jewish background, and all leaders of those communities were also Jewish, and given the fact that the initial growth of the church was mainly amongst Jewish people, and that leadership has a tendency to perpetuate itself:
Is it reasonable to expect that even into the third century, most of the bishops of the church had Jewish roots?
Have studies been done in this issue? What do you think?