Tongue rolling was once believed to be purely a genetic trait. However, Dr. John H. McDonald of the University of Delaware points out that recent studies show that there are factors beyond genetics in determining who can and cannot roll their tongue.
According to Dr. McDonald, twin studies and family studies show that while genetics are involved in tongue rolling, there are also environmental factors to consider. The University of Utah Health Sciences genetics department agrees that there are environmental factors in tongue rolling and further states that tongue rolling can be learned over time. Dr. McDonald notes that between 65 percent and 81 percent of people can roll their tongues, and women are more likely to be able to roll their tongues.