Roll it, flip it, fold it and even mold it into a squiggle. Your tongue can be an acrobat, regardless of whether your parents are capable of the same tricks. 
 
 Every semester, John McDonald, a evolutionary biologist at the University of Delaware, asks his undergraduate students the following question: How many of you were taught in biology class that rolling the tongue is a genetic trait? 
 
 Most of the students raise their hands. They’re wrong. 
 
 In 1940, the prominent geneticist Alfred Sturtevant published a paper saying the ability to roll one’s tongue is based on a dominant gene. In 1952, Philip Matlock disproved Sturtevant’s findings, demonstrating that seven out of 33 identical twins didn’t share their sibling’s gift. If rolling the tongue was genetic, then identical twins would share the trait. Sturtevant later acknowledged his mistake. 
 
 “I am embarrassed to see it listed in some current works as an established Mendelian case,” he wrote in 1965 in his book, “A History of Genetics.” Yet, McDonald says, the myth is still taught in science textbooks and classrooms. See this and this, for example. 
 
 Don’t be discouraged if you aren’t a member of the tongue-rolling elite — some can train their tongues to obey. In fact, one of McDonald’s undergraduate students conducted a small study asking 10 non-tongue-rolling participants to try rolling their tongue each day. After a week of practice, one participant achieved a successful tongue roll. 
 
 This doesn’t mean tongue rolling has no genetic “influence,” McDonald says. More than one gene could contribute to tongue-rolling abilities. Perhaps the same genes that determine the tongue’s length or muscle tone are involved. But there isn’t a single dominant gene that’s responsible. 
 
 While you may think this myth is harmless, McDonald says he’s received emails from kids who don’t share the tongue-rolling status of their parents. Are my parents really my parents, they want to know? He quickly puts their fears to rest. If mom and dad can’t roll their tongues, but you can, don’t worry — chances are you’re still their kid. 
 
 Editor’s note: An earlier version of this piece misidentified the number of study subjects in the small undergraduate study on tongue rolling. It involved 10 students practicing a few minutes a day for a week. ||||| Tongue-rolling: The myth 
 
 Some people can roll their tongue into a tube, and some people can't. This is one of the most common traits that biology teachers use to demonstrate basic genetic principles. Alfred Sturtevant (one of the pioneers of Drosophila genetics) described tongue rolling as a simple two-allele character, with the allele for rolling (usually given the symbol T or R) being dominant over the allele for non-rolling (t or r) (Sturtevant 1940). Many studies have shown that the myth is incorrect, but tongue rolling remains a popular subject in genetics classes. 
 
 The reality 
 
 Tongue rolling as a character 
 
 Rolled tongue; non-rolled tongue. 
 
 Most people, when first asked, either can easily roll their tongue (here called "R"), or cannot roll it at all ("NR"). The proportion of people who can roll their tongue ranges from 65 to 81 percent, with a slightly higher proportion of tongue-rollers in females than in males (Sturtevant 1940, Urbanowski and Wilson 1947, Liu and Hsu 1949, Komai 1951, Lee 1955). However, some people, especially children, cannot roll their tongue when first asked but later learn to do so (Sturtevant 1940). Komai (1951) found that the proportion of tongue-rollers among Japanese schoolchildren increased from 54 percent at ages 6-7 to 76 percent at age 12, suggesting that over 20 percent of the population learns to tongue-roll during that age range. That some people learn to roll their tongues after first being unable to is the first evidence that this is not a simple genetic character. There are also some people who can only slightly roll the edges of their tongue and cannot easily be classified as rollers or non-rollers (Reedy et al. 1971). 
 
 Family studies 
 
 Sturtevant (1940) compared parents and offspring, with the following results: 
 
 Parents R offspring NR offspring R x R 28 5 R x NR 33 22 NR x NR 4 9 
 
 He concluded that tongue rolling was at least partially genetic, with rolling dominant to non-rolling, despite the four R offspring of NR x NR parents. 
 
 Komai (1951) performed a similar study with much larger sample sizes, and found similar results: 
 
 Parents R offspring NR offspring Percent R R x R 928 104 90% R x NR 468 217 68% NR x NR 48 92 34% 
 
 In both family studies, individuals with tongue-rolling parents are much more likely to be tongue-rollers than individuals with non-rolling parents. It is difficult to imagine how the common family environment could influence tongue-rolling, so this resemblance between relatives suggests that there is a large genetic influence on tongue-rolling. 
 
 However, if this trait were a simple one-gene, two-allele genetic character, with rolling completely dominant to non-rolling, then two non-rolling parents could not have a rolling child. Both studies found rolling offspring of non-rolling parents, so the trait must be more complicated than the myth says. The discrepancy could be due to more complicated genetics, involving multiple alleles or multiple genes, or some kind of environmental influence. 
 
 Twin studies 
 
 Matlock (1952) found that out of 33 pairs of monozygotic (identical) twins, 7 pairs consisted of one R and one NR twin. This clearly establishes that there are important non-genetic influences on tongue rolling, and it convinced Sturtevant (1965) that tongue rolling was not determined solely by genetics. Reedy et al. (1971) and Martin (1975) also found numerous pairs of monozygotic twins who differed in tongue rolling. Dizygotic twins were twice as likely to differ in tongue-rolling ability as monozygotic twins (Reedy et al. 1971), which is additional evidence that there is some genetic influence on this trait. 
 
 Matlock (1952) Reedy et al. (1971) Martin (1975) Reedy et al. (1971) DZ twins Both R 18 43 15 81 Both NR 8 11 5 21 R + NR 7 7 8 30 
 
 Conclusion 
 
 Family studies clearly demonstrate that tongue rolling is not a simple genetic character, and twin studies demonstrate that it is influenced by both genetics and the environment. Despite this, tongue rolling is probably the most commonly used classroom example of a simple genetic trait in humans. Sturtevant (1965) said he was "embarrassed to see it listed in some current works as an established Mendelian case." You should not use tongue rolling to demonstrate basic genetics. 
 
 References 
 
 Komai, T. 1951. Notes on lingual gymnastics. Frequency of tongue rollers and pedigrees of tied tongues in Japan. Journal of Heredity 42: 293-297. 
 
 Lee, J. W. 1955. Tongue-folding and tongue-rolling in an American Negro population sample. Journal of Heredity 46: 289-291. 
 
 Liu, T. T., T. C. Hsu. 1949. Tongue-folding and tongue-rolling in a sample of the Chinese population. Journal of Heredity 40: 19-21. 
 
 Martin, N. G. 1975. No evidence for a genetic basis of tongue rolling or hand clasping. Journal of Heredity 66: 179-180. 
 
 Matlock, P. 1952. Identical twins discordant in tongue-rolling. Journal of Heredity 43: 24. 
 
 Sturtevant, A. H. 1940. A new inherited character in man. Proceedings of the National Academy of Sciences USA 26: 100-102. 
 
 Sturtevant, A. H. 1965. A History of Genetics. Harper and Row, New York, NY. 
 
 OMIM entry 
 
 Return to John McDonald's home page
– For anyone who can still proudly recall one factoid learned in high school biology—that the ability to roll one's tongue is genetic—bad news: You learned it wrong. John McDonald, an evolutionary biologist, is out to debunk what he calls a myth about the genetic roots of tongue-rolling, PBS News reports. He says many of his undergrad students walk into class at the University of Delaware believing the skill is passed down through generations, and you can see why in textbooks like Biology for CXC: "Try rolling your tongue longways into a U-shape," the book reads. "Some people can do this, others can't. Tongue-rolling is caused by a dominant gene which we can call T." Pretty specific, yet untrue, says McDonald. The misinformation began in 1940, when geneticist Alfred Sturtevant wrote that tongue rolling was a genetic trait that relies on one dominant gene. His theory was debunked 12 years later by researcher Philip Matlock, who noted that in seven of 33 pairs of identical twins, one twin could roll his tongue while the other couldn't. (His 1952 paper also noted 65% of the population has a tongue-rolling ability.) That ruled out the dominant gene theory, and Sturtevant later backed down. Yet the belief remains so dominant that McDonald says kids have written him fearing they were adopted because they can't tongue-roll like their parents. Genetics may play some role, however. McDonald points to a 1971 study that found non-identical twins were twice as likely to not share tongue-rolling ability as identical ones, "which is additional evidence that there is some genetic influence." Still, "tongue rolling is not a simple genetic character," he writes at the University of Delaware. "Despite this, tongue rolling is probably the most commonly used classroom example of a simple genetic trait in humans." (Speaking of genetics, you and your spouse may have similar DNA.)