What happened is science discovered the existence of Midichlorians, then while studying them they noticed that all the Jedi seemed to have a higher mid-count. That co-relation is a fact they discovered.
The theory that Midichlorians are somehow sentient on their own is a theory that is only presented by Qui-Gon. And when Qui-Gon is talking about having Anakin tested further, Yoda seems to disagree with his "beliefs" when he says: "revealed your opinion is".
Qui-Gon is specifically characterized as a rouge Jedi who rarely follows along with the status quo.
In the end, what we believe about the fact that force sensitives appear to have a higher mid-count is up to us and us alone.