I do unpaid work for my current university in the form of something called "English Clinic." This is essentially a tutoring service in which I sit with students up to two hours a week, helping them in half-hour blocks with whatever English-related problems they bring to me. I actually enjoy the work, despite the lack of pay; the students have been great and the work we do tends not to be boring or dull. Besides, there's little point in complaining since I agreed to do such work when I signed the employment contract.
Today, a student showed me a speech she's going to give for her advanced-level English class. She decided to write on the topic of basketball—why she likes it and what benefits the activity provides. While reading her speech, I came upon this claim: playing basketball makes you grow taller by stimulating the cartilage in your body to gain more mass.
That bowled me over. I had never heard such a claim before, and I immediately filed it under "bullshit that proves Koreans will believe fucking anything," right along with fan death, the notion that blood type correlates with personality, and that eating a tiger's penis will turn you into a sexual dynamo. I actually had to pause, at that point in my reading, so I could try to hash the issue out with the student. I gave her my gut reaction: human growth is largely genetically determined, and it's doubtful that playing basketball can influence your height by more than, oh, a millimeter or two—and if basketball did influence your height, it would be for reasons similar to human "growth" in zero gravity: it's not so much growth, per se, as it is decompression. Perhaps all that jumping does something to stretch the spine. Then again, do basketball players really spend that much time actually jumping while on the court?*
As it turns out, there are websites that earnestly contemplate this question (here's one that looks at the issue and comes to a relatively sane conclusion), although I personally have trouble taking it seriously. I think the student has reversed cause and effect: naturally tall people gravitate toward playing basketball, a sport in which height is an advantage. It's not as though millions of short and average kids grow tall from playing basketball.
But some websites insist that the jumping aspect of basketball somehow stimulates the pituitary to release growth hormone. Others rattle on about stimulated "growth plates" (a new term for me, which I initially thought was voodoo bullshit, but which turned out to be a legitimate anatomical term). I'm trying to see whether the anti-ignorance sites like The Straight Dope have anything on this question, but I've had no luck thus far. (Granted, I've been searching online for only about ten minutes.)
Anyway, I think my intuition is correct and basketball has little to no significant influence on a person's height. It's just screamingly obvious to me that height is genetically determined. You might also say it's hormonally determined, but the glands releasing the relevant hormones are controlled by genes, which brings us back to genetics.
In the end, I told the student she was free to make whatever claims she wanted, and I simply tweaked her speech for grammar and usage. Inwardly, I realized her audience of fellow Koreans would be credulous enough to swallow her outlandish claim unquestioningly. Koreans sometimes are masters of the hermeneutic of suspicion: witness the way a flinty ajumma will squint cautiously at a display of produce as if each fruit or vegetable were potentially poisonous. Witness, too, the ways in which impending FTAs with foreign countries are parsed and re-parsed in public discourse by those who are leery of a more open market. But in other areas of life, Koreans really do believe some ridiculous things, a number of which I listed above. To be fair, there are Americans who believe in the vibratory power of crystals, the efficacy of homeopathic medicine, the existence of ancient astronauts, the sinister nature of the number thirteen, the healing power of prayer, and so on. These beliefs are no less wacky. But basketball? Making you taller? That caught me off guard.
*There's a form of exercise called plyometrics that is all about jumping. It might be useful to ask whether plyometrics has any effect on height. At a guess, it has none: if it did have a significant effect, plyometrics classes would be graduating platoon after platoon of suddenly tall people.