Once upon a time, I had a P. E. professor who said that she's the youngest of a brood of ten and also the tallest. She said that was because, since she was the youngest, she was allowed to roam as she pleased because her parents didn't have time to mollycuddle her anymore.
The truth is, movement does facilitate growth which is why one of the best things parents can do for their kids who want, or can't wait, for them to be taller is to get their kids into exercise or sports (of course, some actually inhibit growth, like gymnastics). Kids who grow up active may not even think of ever using a human growth hormone supplement when they grow up since they'd have realized their maximum potential already through regular activity. Plus, human beings are still evolving so having taller kids and grandkids is actually the norm.
It also doesn't have to be rigorous exercise. Parents can just fly kites, throw Frisbees or jog together. Not all families need to be joining triathlons anyhow. Activity saves a child from obesity and depression too.