You can curl, flip, bend, and even shape it into a wiggly form. Your tongue can act like a gymnast, even if your parents can’t pull off the same stunts. Each semester, John McDonald, an evolutionary biologist at the University of Delaware, asks his undergrads one thing: “Who here was taught in biology that tongue rolling is genetic?”
Most of the class lifts a hand. But they aren’t right.
The origin of the error
In 1940, a famous geneticist named Alfred Sturtevant wrote a paper claiming that the power to roll your tongue relies on a dominant gene. Twelve years later, Philip Matlock proved him wrong by showing that seven out of 33 pairs of identical twins didn’t have the same skill as their sibling. If tongue rolling were actually genetic, identical twins would always have the same ability. Sturtevant eventually admitted he was wrong.
“It embarrasses me to find this cited in modern texts as a proven example of genetics,” he noted in his 1965 book, A History of Genetics. Even so, McDonald points out that schools and science books continue to spread this falsehood. You can look at these specific examples for proof.
Can you learn to roll your tongue?
You shouldn’t feel down if you aren’t currently part of the tongue-rolling club—some people can actually teach their muscles to cooperate. Actually, a student of McDonald’s ran a mini-experiment where she asked 10 people who couldn’t do the trick to keep trying every day. Seven days later, one of the subjects managed to pull off the move.
That doesn’t imply genetics plays zero role in the process, according to McDonald. It is possible that multiple genes work together to enable the skill. Maybe the genetic markers that dictate how long or strong the tongue is are part of the equation. However, no solitary dominant gene controls the whole thing.
Why the myth causes some misunderstandings
You might figure this fable is innocent, but McDonald says he receives emails from children who don’t match their parents when it comes to tongue rolling. They want to know if their parents are truly their biological family. He is quick to calm their nerves. If your mother and father cannot do the trick but you can, do not worry—it is highly likely they are still your parents.
What the Data Actually Shows
Looking at both sets of family research, people whose parents can roll their tongues are far more likely to have the skill themselves compared to those whose parents cannot. It is hard to picture how growing up in the same house would change your tongue’s ability, so this similarity among family members implies that genetics plays a significant role.
But, if this feature relied on a basic single-gene rule where being able to roll is totally dominant, it would be impossible for two parents who cannot do it to have a kid who can. Since both research projects discovered children who could roll their tongues despite having parents who could not, the reality must be trickier than the old story suggests.
This mismatch might happen because the genetics are complex, involving various gene combinations, or perhaps environmental factors affect the outcome.
Time to Update the Textbooks
Research looking at families clearly proves that curling your tongue isn’t just a basic genetic trait, while studies on twins show that both DNA and surroundings play a part.
Even so, this skill is likely the top example schools use to teach simple heredity in humans. Back in 1965, Sturtevant mentioned he felt “ashamed to see it appear in modern books as a proven genetic rule.” You really shouldn’t use this ability to explain the basics of heredity.