Both studies found rolling offspring of non-rolling parents, so the trait must be more complicated than the myth says.
The discrepancy could be due to more complicated genetics, involving multiple alleles or multiple genes, or some kind of environmental influence.
While it has a clear visible sexual undertone with it, that face is seen as a disease virally infecting whichever character has been drawn that way.
Occasionally, a baby who sticks their tongue out more than usual may have an underlying reason.
Last medically reviewed on October 1, 2018.
Matlock 1952 Reedy et al.