But even in that study, evidence against that idea was mounting. Several of the children in the study couldn’t roll their tongues at first, but later learned to do so. In 1951, geneticist Taku Komai noted that while only 54 percent of Japanese schoolchildren could roll their tongues at age six, 76 percent could do so at age 12. That meant that more than 20 percent of kids may learn to tongue-roll in grade school, and that’s a big strike against the idea that the skill is purely genetic.
In the case of tongue rolling, even with identical genes, identical twins didn’t all share the skill. That shows that while tongue rolling probably has some genetic component, it’s not as simple as science class made it out to be. When it comes to learning genetics, stick to attached earlobes and chin clefts. Tongue rolling is a skill all its own.