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Genetics of tongue rolling
Summary
Biology teachers love to use tongue rolling as a fun, easily observable example of human character that they say is a simple genetic trait, with the ability to roll your tongue into a tube being dominant. This is not true! It's been known since the 1950s that tongue rolling is NOT a simple genetic trait, as shown by multiple studies of families and twins. Genes may have some influence on your ability to roll your tongue, but the environment also has an effect. If you can roll your tongue but neither of your parents can, don't worry, that doesn't meant that they're not your biological parents. And if you're a biology teacher, please, please stop using tongue rolling in your classes.
Are there two kinds of people, rollers and non-rollers?
Tongue rolling is probably the most common human trait used to teach genetics. When I ask upper-level college biology students whether a previous biology teacher has ever asked them to roll their tongue, almost everyone says yes. Most people, when first asked, either can easily roll their tongue into a tube (here called "R"), or cannot roll it at all ("NR"). Reedy et al. (1971) put 5% of people in an intermediate category, able to slightly elevate the sides of their tongue, but most studies have classified everyone as either a roller or a non-roller. At any one time, tongue rolling is a trait with most people falling into just two distinct categories, rollers vs. non-rollers; this is probably one of the reasons biology teachers like using it.
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 learned to tongue-roll during that age range. Tahir et al. (2014) found that the proportion of tongue rollers increased from 42 percent in 7 to 9 year olds to 57 percent in 11 to 12 year olds.
Several years ago, I had two students (Danielle McKenna and Kevin Lozo) find volunteers who couldn't roll their tongues, then ask them to practice. Without any instruction in how to "practice" tongue roling, and without any real incentive, two out of 17 non-rollers learned to roll their tongues, and several other acheived partial rolls. It is clear that people can change from non-roller to roller, which means that whether you are a roller or non-roller depends on more than genetics.
Family studies
Alfred Sturtevant (one of the pioneers of Drosophila genetics) first described tongue rolling as a genetic trait. He compared parents and offspring, with the following results:
| Parents | R offspring | NR offspring |
|---|---|---|
| R×R | 28 | 5 |
| R×NR | 33 | 22 |
| NR×NR | 4 | 9 |
If rolling really was caused by a dominant allele, two non-rolling parents couldn't have a rolling child, but Sturtevant's data showed four of these children. He therefore concluded that tongue rolling "may" be due to a dominant allele at a single gene, "with the fairly frequent occurrence of additional complications."
Komai (1951) performed a similar study with much larger sample sizes, and found similar results:
| Parents | R offspring | NR offspring | Percent R |
|---|---|---|---|
| R×R | 928 | 104 | 90% |
| R×NR | 468 | 217 | 68% |
| NR×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 rolling can't be a simple dominant trait. 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 |
Tongue rolling and academic field
Azimi-Garaani and Beardmore (1979) found that the proportion of tongue rollers was higher for undergraduate students at University College Swansea in the life sciences than in the arts. Bell and Clegg (1983) found the same pattern at Aberdeen University, while Medyckyj and Cook (1983) did not find a difference in tongue rolling proportions between science and art students at Manchester University. I don't know why there would be a relation between academic field of study and tongue rolling, and I don't know why it would be different between different universities.
Further research
It would be interesting to see if tongue rolling is something that everyone could learn. When my students tried to get volunteers to learn to roll their tongues, there was no real incentive for the non-rollers to spend much time or effort; it might be necessary to offer a cash reward for people who learned to roll. And doing this study on children as well as adults would be interesting.
Ancestry.com asks their DNA customers whether they can roll their tongues, and I think 23andMe asks their customers too. They therefore have the data to do genome-wide association studies to see if any genes are associated with tongue rolling, but unfortunately have not published any results.
I don't know anything about tongue musculature, but if possible, it would be interesting to see if there's an anatomical difference between the tongues of rollers and non-rollers; maybe ultrasound would be enough to see the muscles?
I suppose someone should look into the greater proportion of tongue rollers in science students vs. non-science students that Azimi-Garaani and Beardmore (1979) and Bell and Clegg (1983) found. I suspect that whether someone has heard about tongue rolling in a previous class may have something to do with it, so any study should include questions about that.
References
Azimi-Garakini, C., and J. A. Beardmore 1979. An association between tongue-rolling phenotypes and subjects of study of undergraduates. Journal of Biosocial Science 11: 193-199.
Bell, L. M., and E. J. Clegg. 1983. An association between tongue-rolling phenotypes and subjects of study of undergraduates: a further comment. Journal of Biosocial Science 15: 519-521.
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., and 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.
Medycyj, M., and L. M. Cook. 1983. An association between tongue-rolling phenotypes and subjects of study of undergraduates: a comment. Journal of Biosocial Science 15: 107-108.
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.
Tahir, H.M., J. Aqueel, R. Mishal, M. M. Ahsan, M. Bilal, and S. Y. Khan. 2014. Some interesting facts about tongue rolling trait in humans. Pakistan Journal of Zoology 46: 1173-1175.
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This page was last revised October 26, 2026. ©2026 by John H. McDonald. Content is available under the Creative Commons Attribution-Noncommercial license.