Rolling your tongue is not a genetic trait. Most of the people reading this were told, at some point during their schooling, that it was. At last you can read the paper that started the myth, and find out how quickly it was disproved.
Some of us had our tiny egos crushed in the third grade when a teacher, during a science presentation, tried to explain genetics by having the entire classroom roll their tongues. When some people couldn’t, the teacher announced that the ability to roll one’s tongue was genetic. The flat-tongued among us would never be able to twist their tongues into a roll, and should just give up. The inspiration from that lesson came from “A New Inherited Character in Man,” published in 1940.
By 1952, the substance of the paper was discredited, although the authors of the paper did a decent job in rounding up 280 subjects, 65% of which were able to curl their tongues. After analyzing the family history of tongue curlers and non-tongue curlers alike, the researchers believed that the ability was at least in part the product of genetics. Mothers and fathers had equal influence on their offspring’s ability to curl their tongues, and the sets of identical twins that the researchers studied both had the same ability to curl their tongues. The fact that genetics determined tongue dexterity (linguarity?), caught the popular imagination, and held up scientifically… for 12 years.
Read full, original article: This Paper About Tongues and Genetics Fooled the Whole World