Asked by: Curtis Mortimer, Northampton
Scientists aren’t sure. There is a long-standing myth that tongue rolling is controlled by a single gene, but this was based on a single piece of flawed research and was debunked as early as 1952.
Tongue rolling seems to be an ability that comes with practice, not something you are born with. The most likely explanation is that because tongue rolling isn’t useful for speaking, whistling, talking, kissing or anything else apart from showing off at parties, some of us just never got around to mastering the skill.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.