Tongue Rolling
What Do Classrooms Say?
Classrooms teach that tongues can be divided into two clear categories, rolling and non-rolling. People who can roll their tongues have the ability to fold the lateral edges of their tongue upwards. Those who cannot roll their tongues cannot do this. According to textbooks, the ability to roll ones tongue (R) is the dominant trait while the inability to roll ones tongue is the recessive trait (NR). |
Rolling Non-Rolling
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What Does the Research Say?
Parents R offspring NR offspring Percent R
RxR 928 104 90%
RxNR 468 217 68%
NRxNR 48 92 34%
2. There are numerous twin studies done analyzing the ability to roll tongues of twins. Three studies done with identical twins had data where one twin had the ability to roll his/her tongue and the other twin did not. The results of the three studies (Matlock (1952), Reedy (1971), Martin (1975)) are listed below: ________________________________________________
Parents Matlock (1952) Reedy (1971) Martin (1975)
Both R 18 43 15
Both NR 8 11 21
R & NR 7 8 30 _
Conclusion:
The studies done clearly demonstrate that tongue rolling is not a simple genetic character. If it were, two tongue rolling parents wouldn't be able to have children who could not roll their tongues and identical twins would have the same tongue rolling ability. Tongue rolling is most likely influenced by both genetics and the environment.
- Komai (1951) performed a study comparing the ability to roll tongues between parents and their offspring. He concluded that tongue rolling was at least partially genetic, with rolling dominant to non-rolling. These are his results:
Parents R offspring NR offspring Percent R
RxR 928 104 90%
RxNR 468 217 68%
NRxNR 48 92 34%
2. There are numerous twin studies done analyzing the ability to roll tongues of twins. Three studies done with identical twins had data where one twin had the ability to roll his/her tongue and the other twin did not. The results of the three studies (Matlock (1952), Reedy (1971), Martin (1975)) are listed below: ________________________________________________
Parents Matlock (1952) Reedy (1971) Martin (1975)
Both R 18 43 15
Both NR 8 11 21
R & NR 7 8 30 _
Conclusion:
The studies done clearly demonstrate that tongue rolling is not a simple genetic character. If it were, two tongue rolling parents wouldn't be able to have children who could not roll their tongues and identical twins would have the same tongue rolling ability. Tongue rolling is most likely influenced by both genetics and the environment.
Sources:
Jones, Kristin. "Genetics Unit." Biology Class. Novi High School, Novi. 8 Dec. 2010. Lecture.
Komai, T. 1951. Notes on lingual gymnastics. Frequency of tongue rollers and pedigrees of tied tongues in Japan. Journal of Heredity 42: 293-297.
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.
Jones, Kristin. "Genetics Unit." Biology Class. Novi High School, Novi. 8 Dec. 2010. Lecture.
Komai, T. 1951. Notes on lingual gymnastics. Frequency of tongue rollers and pedigrees of tied tongues in Japan. Journal of Heredity 42: 293-297.
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.