|MadSci Network: Genetics|
Well, I checked OMIM (Online Mendelian Inheritance in Man) which is a database of traits and the known genetics thereof. Here's the address: OMIM Here's my interpretation of the summary given there: the answer is still a little unclear, although evidence against a genetic basis is mounting. The original paper describing dominant inheritance was published by a very respected geneticist (Sturtevant 1940), but the follow up paper by Martin (1975) found little evidence for a genetic basis. Martin studied the concordance rate in twins, which is also a classic study design for inheritance patterns. Given the lack of consensus in the literature, here's my opinion. I seem to recall spending a while trying to figure out how to roll my tongue, back in the first grade. Eventually I figured it out. Therefore the trait is definitely learned, even if the capacity for rolling is inherited. Further evidence for a learned basis of tongue gymnastic ability is the cloverleaf tongue. My ten year old brother in law introduced this one to me: try rolling your tongue, and then roll the tip back on itself. If you can roll your tongue, with a little practice this will make the end of your tongue a W or "cloverleaf" shape. Unless you learn this trick from someone, I doubt you'd ever discover it by yourself. However, the fact that you can learn to do tricks with your tongue doesn't rule out a genetic basis for the ability as well. My mother definitely cannot roll her tongue, no matter how she tries. Perhaps she didn't learn at a young enough age, or perhaps her genetics prevent her from doing it. At this point I'd say the issue is unresolved, although trending toward a learned basis. Chris Carlson firstname.lastname@example.org
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