Ruling out teacher impact on height without testing is perhaps not strictly scientific?

We really don't know what is true unless we test it. I know it sounds ridiculous but it's not beyond the realms of possibility that teacher opinion of student capabilities influences social status which in turn influences release of growth hormones which influence height. Aren't there other species which grow when they rise to the top of the pack as growth hormones are released to assist in maintaining that status? Not saying it's likely but if left untested we cannot rule that out. There have been plenty of surprises in science when we went and actually tested what we previously presumed to be implausible.