Yeah, I dislike comments like the parent comment. The statement is clearly based on his/her own intuitive understanding based on anecdotal experience; something that can be useful in forming-opinions/developing-understanding , but shouldn't be asserted as fact.
It's particularly annoying because a statement like that isn't easily refuted; I mean, after all, a child who literally doesn't move at all has no physical activity and therefore doesn't grow(dies pretty quick actually), whereas a child who exercises regularly does grow, so the MUST be a correlation between exercise and height right? Ultimately, yes, there obviously is _some_ correlation, how much of a correlation and exactly how exercise reflects on a humans development are left unanswered though.