Exactly what I was thinking. Did the study control for genetic effects? The study compared "weightlifters" and "runners" - people who have presumably already be

Exactly what I was thinking. Did the study control for genetic effects? The study compared "weightlifters" and "runners" - people who have presumably already been pursuing the activity for some time, instead of of being randomly assigned to such an experimental condition. So we might expect that genetically stronger people (with stronger tongues) would gravitate toward weightlifting, with the same trend for self-identified "runners" and endurance.